diff --git a/CMakeLists.txt b/CMakeLists.txt
index 577049484..30f7af961 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -316,15 +316,15 @@ add_prefix(MP_HEADERS include/mp/
   model-mgr-base.h model-mgr-with-pb.h
   model-mgr-with-std-pb.h model-mgr-with-std-pb.hpp
   nl.h nl-reader.h option.h os.h problem.h problem-builder.h
-  valcvt-base.h valcvt-node.h valcvt-link.h valcvt.h
+  presolve-base.h presolve-node.h presolve-bridge.h presolve.h
   rstparser.h safeint.h sol.h
   solver.h solver-opt.h solver-base.h solver-io.h solver-app-base.h solver-app.h
   suffix.h utils-file.h utils-hash.h utils-hash-stream.h utils-string.h)
 
 add_prefix(MP_FLAT_HEADERS include/mp/flat/
-  constr_base.h constr_keeper.h constr_hash.h
-  constr_std.h constr_static.h constr_functional.h
-  constr_algebraic.h constr_general.h
+  constraint_base.h constraint_keeper.h constraint_hash.h
+  constraints_std.h constraints_static.h constraints_functional.h
+  constraints_algebraic.h constraints_general.h
   context.h
   converter.h converter_model.h convert_functional.h
   eexpr.h expr_algebraic.h expr_affine.h expr_quadratic.h
diff --git a/doc/rst/components.rst b/doc/rst/components.rst
index f6b67ecc5..ef7804bf9 100644
--- a/doc/rst/components.rst
+++ b/doc/rst/components.rst
@@ -156,20 +156,8 @@ solver messages and status reporting,
 simplex basis statuses, and other suffix I/O.
 Their solver-specific subclasses can be customized for a particular solver.
 They rely on the :ref:`model-manager` interface
-for model and solution I/O.
-
-As an example, if the driver should read and write simplex basis status suffixes,
-the derived Backend class can declare
-
-.. code-block:: c++
-
-    ALLOW_STD_FEATURE( BASIS, true )
-    SolutionBasis GetBasis() override;
-    void SetBasis(SolutionBasis ) override;
-
-and define the `GetBasis`, `SetBasis` methods.
-See the classes' documentation
-for further details.
+for model and solution I/O. See the classes' documentation
+for details.
 
 
 .. _solver-classes:
@@ -260,19 +248,6 @@ via the solver's modeling API wrapper:
 * `mp::BasicFlatModelAPI` is the interface via which `mp::FlatConverter` addresses
   the underlying solver. A subclassed wrapper, such as `mp::GurobiModelAPI`,
   signals its accepted constraints and which model conversions are preferable.
-  For example, `GurobiModelAPI` declares the following in order to natively
-  receive the logical OR constraint:
-
-  .. code-block:: c++
-
-      ACCEPT_CONSTRAINT(OrConstraint,
-        Recommended,                       // Driver recommends native form
-        CG_General)                        // Constraint group for suffix exchange
-      void AddConstraint(const OrConstraint& );
-
-  By default, if the driver does not mark a constraint as acceptable,
-  `mp::FlatConverter` and its descendants attempt to simplify it. See the
-  classes' documentation for further details.
 
 * :ref:`value-presolver` transforms solutions and suffixes between the
   original NL model and the flat model.
@@ -283,7 +258,7 @@ via the solver's modeling API wrapper:
 Value Presolver
 ~~~~~~~~~~~~~~~
 
-Class `mp::pre::ValuePresolver` manages transformations of solutions and suffixes
+Class `mp::pre::Presolver` manages transformations of solutions and suffixes
 between the original NL model and the converted model. For driver architectures
 with :ref:`model-manager`, the value presolver object should be shared between
 the model converter and the :ref:`Backend <backend-classes>` to enable
diff --git a/doc/rst/details.rst b/doc/rst/details.rst
index 0b61bc03e..bfe9d8fa8 100644
--- a/doc/rst/details.rst
+++ b/doc/rst/details.rst
@@ -17,13 +17,6 @@ Namespace mp
    :members:
 
 
-Namespace mp::pre
------------------
-
-.. doxygennamespace:: mp::pre
-   :members:
-
-
 Namespace fmt
 -------------
 
diff --git a/doc/rst/model-guide.rst b/doc/rst/model-guide.rst
index 178ab4501..0b87360d7 100644
--- a/doc/rst/model-guide.rst
+++ b/doc/rst/model-guide.rst
@@ -205,8 +205,8 @@ to the solver natively
 (if supported; e.g., Gurobi options *acc:and*, *acc:or*).
 
 
-SOS constraints and non-contiguous variable domains
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+SOS variable domains
+~~~~~~~~~~~~~~~~~~~~
 
 SOS1 is mainly relevant for models that restrict some variables to take a
 value from an arbitrary list of values. A simple example:
@@ -218,11 +218,8 @@ value from an arbitrary list of values. A simple example:
 An appropriate SOS1 representation will be
 automatically generated from this declaration.
 
-SOS2 are one of the two ways to linearize
-:ref:`piecewise-linear expressions <piecewize-linear-expr>` by AMPL.
-
 It is possible to specify SOS1 or SOS2 variables and corresponding "reference rows"
-explicitly using AMPL suffixes .sos(no) and .(sos)ref,
+explicitly using AMPL suffixes .sosno and .ref,
 as described in the solver documentation.
 However this requires some study to understand whether SOS1/2 is appropriate
 and how to apply it, and we don't recommend going to that trouble unless you
@@ -246,8 +243,6 @@ or passed to the solver natively
 (if supported; e.g., Gurobi options *acc:min*, *acc:max*, *acc:abs*).
 
 
-.. _piecewize-linear-expr:
-
 Piecewise-linear expressions
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/include/mp/ampls-c-api.h b/include/mp/ampls-c-api.h
index a8ad3f54f..273b42c74 100644
--- a/include/mp/ampls-c-api.h
+++ b/include/mp/ampls-c-api.h
@@ -1,14 +1,9 @@
 #ifndef AMPLS_C_INTERFACE_H
 #define AMPLS_C_INTERFACE_H
 
-#include <stddef.h>
-
 /*
  * A generic C API for MP
  */
-
-#include <stddef.h>    // for size_t
-
 #ifdef _WIN32
 #define AMPLS_C_EXPORT __declspec(dllexport)
 #else
@@ -50,18 +45,4 @@ AMPLS_C_EXPORT void AMPLSAddMessage(AMPLS_MP_Solver* slv, const char* msg);
 const char* const * AMPLSGetMessages(AMPLS_MP_Solver* slv);
 
 
-/// Set of callbacks provided to a driver for licensing issues
-typedef struct CCallbacks_T {
-  /// If provided, replacement function to create solver environment
-  /// for a given solver.
-  void* (*init)(); 
-  /// Check if model sizes are allowed; throw if not.
-  /// Parameters: n_vars, n_alg_con, n_log_con
-  void (*check)(size_t, size_t, size_t);
-  /// Return additional text to be displayed on '-v' output
-  const char* (*additionalText)();
-  /// Function called after failures to provide additional diagnostics
-  void (*diagnostics)();
-} CCallbacks;
-
 #endif // AMPLS_C_INTERFACE_H
diff --git a/include/mp/ampls-cpp-api.h b/include/mp/ampls-cpp-api.h
index eaaa7807c..dc3473a70 100644
--- a/include/mp/ampls-cpp-api.h
+++ b/include/mp/ampls-cpp-api.h
@@ -28,9 +28,6 @@ AMPLS_MP_Solver* AMPLS__internal__Open(std::unique_ptr<mp::BasicBackend> p_be,
                           const char* slv_opt);
 
 /// Shut down solver instance. Internal only.
-/// Deallocate the mp-related info and the structure itself.
-/// Before calling this function, a solver-specific implementation should
-/// delete solver_info_ and user_info_ if allocated.
 void AMPLS__internal__Close(AMPLS_MP_Solver* slv);
 
 /// Retrieve the Backend
diff --git a/include/mp/backend-base.h b/include/mp/backend-base.h
index 01f5cd817..95d8b774a 100644
--- a/include/mp/backend-base.h
+++ b/include/mp/backend-base.h
@@ -2,10 +2,7 @@
 #define BACKEND_BASE_H
 
 #include <string>
-
-extern "C" {
-  #include "mp/ampls-c-api.h" // for CCallbacks
-}
+#include <functional>
 
 #include "mp/solver-base.h"
 
@@ -79,13 +76,26 @@ class BasicBackend : public BasicSolver {
   /// Chance to consider options immediately (open cloud, etc)
   virtual void FinishOptionParsing() { }
 
-  /// Callbacks typedef
-  using Callbacks = CCallbacks;
+  /// Callbacks, e.g., for licensing information
+  struct Callbacks {
+    /// If given, has the custom solver GetEnv() method
+    std::function<void*()> cb_initsolver_;
+
+    /// If given, should be called after reading the NL (header)
+    /// with n_vars, n_algebraic_constr, n_logical_constr
+    std::function<void (size_t, size_t, size_t)> cb_checkmodel_;
+
+    /// If given, provides the license description
+    std::function<const char*()> cb_license_text_;
+
+    /// If given, the function is called to provide additional
+    // diagnostics if a solver environment cannot be created
+    std::function<void()> cb_diagnostics_;
+  };
 
   /// Obtain callbacks
   Callbacks& GetCallbacks() { return callbacks_; }
 
-
 private:
   Callbacks callbacks_;
 };
diff --git a/include/mp/backend-mip.h b/include/mp/backend-mip.h
index a1437b04a..17a361670 100644
--- a/include/mp/backend-mip.h
+++ b/include/mp/backend-mip.h
@@ -85,9 +85,9 @@ class MIPBackend : public BaseBackend
   /// The basis statuses of vars and cons.
   /// MIPBackend handles them in postsolved form (for the NL model)
   /// Impl has to perform value pre- / postsolve if needed
-  /// Getter (returns unpresolved basis)
+  /// Getter (unpresolved)
   virtual SolutionBasis GetBasis() { return {}; }
-  /// Setter (takes unpresolved basis)
+  /// Setter (unpresolved)
   virtual void SetBasis(SolutionBasis )
   { MP_UNSUPPORTED("MIPBackend::SetBasis"); }
   /**
diff --git a/include/mp/backend.h b/include/mp/backend.h
index 222337125..872017676 100644
--- a/include/mp/backend.h
+++ b/include/mp/backend.h
@@ -57,7 +57,7 @@ DEFAULT_STD_FEATURES_TO( false )
 
 namespace mp {
 
-/// Solution (normally unpresolved)
+/// Basis status values of a solution (unpresolved)
 struct Solution {
   /// primal
   std::vector<double> primal;
@@ -186,7 +186,7 @@ class Backend :
   void ReadNL(const std::string& nl_filename,
               const std::string& filename_no_ext) override {
     GetMM().ReadNLModel(nl_filename, filename_no_ext,
-                        GetCallbacks().check);
+                        GetCallbacks().cb_checkmodel_);
   }
 
   /// Input warm start, suffixes, and all that can modify the model.
@@ -846,7 +846,7 @@ class Backend :
     this->set_long_name( fmt::format("{} {}", name, version ) );
     this->set_version( fmt::format("AMPL/{} Optimizer [{}]",
                                    name, version ) );
-    auto lic_cb = GetCallbacks().additionalText;
+    auto lic_cb = GetCallbacks().cb_license_text_;
     if (lic_cb)
       this->set_license_info(lic_cb());
   }
diff --git a/include/mp/flat/constr_base.h b/include/mp/flat/constraint_base.h
similarity index 100%
rename from include/mp/flat/constr_base.h
rename to include/mp/flat/constraint_base.h
diff --git a/include/mp/flat/constr_hash.h b/include/mp/flat/constraint_hash.h
similarity index 99%
rename from include/mp/flat/constr_hash.h
rename to include/mp/flat/constraint_hash.h
index f32fff9eb..f12e93f13 100644
--- a/include/mp/flat/constr_hash.h
+++ b/include/mp/flat/constraint_hash.h
@@ -8,7 +8,7 @@
 #include <vector>
 
 #include "mp/utils-hash-stream.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 #include "mp/flat/expr_affine.h"
 
 namespace std {
diff --git a/include/mp/flat/constr_keeper.h b/include/mp/flat/constraint_keeper.h
similarity index 98%
rename from include/mp/flat/constr_keeper.h
rename to include/mp/flat/constraint_keeper.h
index 74332cac8..d9eca33f0 100644
--- a/include/mp/flat/constr_keeper.h
+++ b/include/mp/flat/constraint_keeper.h
@@ -9,9 +9,9 @@
 
 #include "mp/common.h"
 #include "mp/flat/model_api_base.h"
-#include "mp/flat/constr_hash.h"
+#include "mp/flat/constraint_hash.h"
 #include "mp/flat/redef/redef_base.h"
-#include "mp/valcvt-node.h"
+#include "mp/presolve-node.h"
 
 namespace mp {
 
@@ -318,10 +318,10 @@ class ConstraintKeeper : public BasicConstraintKeeper {
     for (const auto& cont: cons_) {
       if (!cont.IsBridged()) {
         static_cast<Backend&>(be).AddConstraint(cont.con_);
-        GetConverter().GetCopyLink().
+        GetConverter().GetCopyBridge().
             AddEntry({
                        GetValueNode().Select(con_index),
-                       GetConverter().GetValuePresolver().GetTargetNodes().
+                       GetConverter().GetPresolver().GetTargetNodes().
                          GetConValues()(con_group).Add()
                      });
       }
diff --git a/include/mp/flat/constr_algebraic.h b/include/mp/flat/constraints_algebraic.h
similarity index 99%
rename from include/mp/flat/constr_algebraic.h
rename to include/mp/flat/constraints_algebraic.h
index b41ed399f..1d403cfae 100644
--- a/include/mp/flat/constr_algebraic.h
+++ b/include/mp/flat/constraints_algebraic.h
@@ -8,7 +8,7 @@
 #include <string>
 #include <cmath>
 
-#include "mp/flat/constr_base.h"
+#include "mp/flat/constraint_base.h"
 #include "mp/flat/expr_quadratic.h"
 
 
diff --git a/include/mp/flat/constr_functional.h b/include/mp/flat/constraints_functional.h
similarity index 99%
rename from include/mp/flat/constr_functional.h
rename to include/mp/flat/constraints_functional.h
index 4b7186847..b2786375c 100644
--- a/include/mp/flat/constr_functional.h
+++ b/include/mp/flat/constraints_functional.h
@@ -5,7 +5,7 @@
   * Functional flat constraints
   */
 
-#include "mp/flat/constr_static.h"
+#include "mp/flat/constraints_static.h"
 
 
 namespace mp {
diff --git a/include/mp/flat/constr_general.h b/include/mp/flat/constraints_general.h
similarity index 98%
rename from include/mp/flat/constr_general.h
rename to include/mp/flat/constraints_general.h
index 18fa40549..732254097 100644
--- a/include/mp/flat/constr_general.h
+++ b/include/mp/flat/constraints_general.h
@@ -8,7 +8,7 @@
 #include <vector>
 #include <string>
 
-#include "mp/flat/constr_algebraic.h"
+#include "mp/flat/constraints_algebraic.h"
 
 
 namespace mp {
diff --git a/include/mp/flat/constr_static.h b/include/mp/flat/constraints_static.h
similarity index 63%
rename from include/mp/flat/constr_static.h
rename to include/mp/flat/constraints_static.h
index 4e4780ced..fc639fd66 100644
--- a/include/mp/flat/constr_static.h
+++ b/include/mp/flat/constraints_static.h
@@ -5,7 +5,7 @@
   * Static (non-functional) flat constraints
   */
 
-#include "mp/flat/constr_algebraic.h"
-#include "mp/flat/constr_general.h"
+#include "mp/flat/constraints_algebraic.h"
+#include "mp/flat/constraints_general.h"
 
 #endif // CONSTRAINTS_STATIC_H
diff --git a/include/mp/flat/constr_std.h b/include/mp/flat/constraints_std.h
similarity index 63%
rename from include/mp/flat/constr_std.h
rename to include/mp/flat/constraints_std.h
index 50ab5b54c..726affdca 100644
--- a/include/mp/flat/constr_std.h
+++ b/include/mp/flat/constraints_std.h
@@ -6,7 +6,7 @@
   * flat constraints
   */
 
-#include "mp/flat/constr_static.h"
-#include "mp/flat/constr_functional.h"
+#include "mp/flat/constraints_static.h"
+#include "mp/flat/constraints_functional.h"
 
 #endif // STD_CONSTR_H
diff --git a/include/mp/flat/converter.h b/include/mp/flat/converter.h
index b97708f5c..fd9b481b9 100644
--- a/include/mp/flat/converter.h
+++ b/include/mp/flat/converter.h
@@ -12,9 +12,9 @@
 #include "mp/solver-base.h"
 #include "mp/flat/converter_model.h"
 #include "mp/flat/convert_functional.h"
-#include "mp/flat/constr_keeper.h"
-#include "mp/flat/constr_std.h"
-#include "mp/valcvt.h"
+#include "mp/flat/constraint_keeper.h"
+#include "mp/flat/constraints_std.h"
+#include "mp/presolve.h"
 #include "mp/flat/redef/std/range_con.h"
 
 namespace mp {
@@ -881,7 +881,7 @@ class FlatConverter :
 
   void FinishModelInput() {
     MPD( ConvertModel() );
-    if (relax())              // TODO value presolve link?
+    if (relax())              // TODO bridge?
       GetModel().RelaxIntegrality();
     GetModel().PushModelTo(GetModelAPI());
   }
@@ -909,9 +909,9 @@ class FlatConverter :
   const ModelAPI& GetModelAPI() const { return modelapi_; }
   ModelAPI& GetModelAPI() { return modelapi_; }
 
-  /// Expose ValuePresolver
-  const pre::ValuePresolver& GetValuePresolver() const { return value_presolver_; }
-  pre::ValuePresolver& GetValuePresolver() { return value_presolver_; }
+  /// Expose Presolver
+  const pre::Presolver& GetPresolver() const { return presolver_; }
+  pre::Presolver& GetPresolver() { return presolver_; }
 
 private:
   std::unordered_map<double, int> map_fixed_vars_;
@@ -949,7 +949,7 @@ class FlatConverter :
 
   /// Reuse Presolver's target nodes for all variables
   pre::ValueNode& GetVarValueNode()
-  { return GetValuePresolver().GetTargetNodes().GetVarValues().MakeSingleKey(); }
+  { return GetPresolver().GetTargetNodes().GetVarValues().MakeSingleKey(); }
 
   /// Constraint type's Value Node
   template <class Constraint>
@@ -1067,7 +1067,7 @@ class FlatConverter :
 private:
   void InitOwnOptions() {
     GetEnv().AddOption("cvt:pre:all",
-        "0/1*: Set to 0 to disable most presolve in the flat converter.",
+        "0/1*: Set to 0 to disable all presolve in the flat converter.",
         options_.preprocessAnything_, 0, 1);
     GetEnv().AddOption("cvt:pre:eqresult",
         "0/1*: Preprocess reified equality comparison's boolean result bounds.",
@@ -1099,8 +1099,8 @@ class FlatConverter :
 
 private:
   ModelAPIType modelapi_;      // We store modelapi in the converter for speed
-  pre::ValuePresolver value_presolver_;
-  pre::CopyLink copy_link_ { GetValuePresolver() };
+  pre::Presolver presolver_;
+  pre::CopyBridge copy_bridge_ { GetPresolver() };
 
 
 protected:
@@ -1232,8 +1232,8 @@ class FlatConverter :
   INSTALL_ITEM_CONVERTER(RangeQuadraticConstraintConverter)
 
 public:
-  /// Presolve link copying values between model items
-  pre::CopyLink& GetCopyLink() { return copy_link_; }
+  /// Presolve bridge copying values between model items
+  pre::CopyBridge& GetCopyBridge() { return copy_bridge_; }
 };
 
 
diff --git a/include/mp/flat/converter_model.h b/include/mp/flat/converter_model.h
index d2fbf7416..4ed9ba3ac 100644
--- a/include/mp/flat/converter_model.h
+++ b/include/mp/flat/converter_model.h
@@ -7,8 +7,8 @@
 #include <cmath>
 
 #include "mp/flat/obj_std.h"
-#include "mp/flat/constr_std.h"
-#include "mp/flat/constr_keeper.h"
+#include "mp/flat/constraints_std.h"
+#include "mp/flat/constraint_keeper.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/model_api_base.h b/include/mp/flat/model_api_base.h
index dd2a29895..d1ad83e8e 100644
--- a/include/mp/flat/model_api_base.h
+++ b/include/mp/flat/model_api_base.h
@@ -28,7 +28,7 @@
 
 #include "mp/arrayref.h"
 #include "mp/common.h"
-#include "mp/flat/constr_base.h"
+#include "mp/flat/constraint_base.h"
 #include "mp/flat/obj_std.h"
 
 namespace mp {
diff --git a/include/mp/flat/model_api_connect.h b/include/mp/flat/model_api_connect.h
index 36a0f3edd..878b02efb 100644
--- a/include/mp/flat/model_api_connect.h
+++ b/include/mp/flat/model_api_connect.h
@@ -26,7 +26,7 @@ template <class ModelAPI,
           class Backend>
 std::unique_ptr<BasicModelManager>
 CreateModelMgrWithFlatConverter(Backend& gc, Env& e,
-                     pre::BasicValuePresolver*& pPre) {
+                     pre::BasicPresolver*& pPre) {
   using SolverFlatCvt = FlatCvtImpl<FlatConverter, ModelAPI>;
   using SolverProblemFlattener = mp::ProblemFltImpl<
     mp::ProblemFlattener, mp::Problem, SolverFlatCvt>;
@@ -36,7 +36,7 @@ CreateModelMgrWithFlatConverter(Backend& gc, Env& e,
   pcvt->GetFlatCvt().GetModelAPI().set_other(&gc);
   gc.set_other(
         &pcvt->GetFlatCvt().GetModelAPI());
-  pPre = &pcvt->GetFlatCvt().GetValuePresolver();
+  pPre = &pcvt->GetFlatCvt().GetPresolver();
   return res;
 }
 
diff --git a/include/mp/flat/problem_flattener.h b/include/mp/flat/problem_flattener.h
index 737d4f855..8a05c6da9 100644
--- a/include/mp/flat/problem_flattener.h
+++ b/include/mp/flat/problem_flattener.h
@@ -10,9 +10,9 @@
 #include "mp/converter-base.h"
 #include "mp/expr-visitor.h"
 #include "mp/flat/eexpr.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 #include "mp/flat/obj_std.h"
-#include "mp/valcvt.h"
+#include "mp/presolve.h"
 
 
 namespace mp {
@@ -109,7 +109,6 @@ class ProblemFlattener :
   }
 
 protected:
-  /// Convert problem items
   void ConvertStandardItems() {
     ////////////////////////// Variables
     ConvertVars();
@@ -150,18 +149,16 @@ class ProblemFlattener :
       types[i] = mpvar.type();
     }
     auto vnr = GetFlatCvt().AddVars(lbs, ubs, types);
-    GetCopyLink().AddEntry({
-          GetValuePresolver().GetSourceNodes().GetVarValues().MakeSingleKey().
+    GetCopyBridge().AddEntry({
+          GetPresolver().GetSourceNodes().GetVarValues().MakeSingleKey().
                                Add(lbs.size()),
           vnr });
   }
 
-  /// Convert a common expr
   void Convert(typename ProblemType::MutCommonExpr ) {
     /// Converting on demand, see VisitCommonExpr
   }
 
-  /// Convert an objective
   void Convert(typename ProblemType::MutObjective obj) {
       auto le = ToLinTerms(obj.linear_expr());
       NumericExpr e = obj.nonlinear_expr();
@@ -190,11 +187,10 @@ class ProblemFlattener :
                                std::move(eexpr.GetQPTerms())});
   }
 
-  /// Convert an algebraic constraint
   void ConvertAlgCon(int i) {
     auto pr = PrepareAlgConstraint(i);
     auto nr = AddAlgebraicConstraint(pr);
-    AddCopyLinkFromSource(nr);
+    AddCopyBridgeFromSource(nr);
   }
 
   /// Preparation info
@@ -239,7 +235,7 @@ class ProblemFlattener :
 
   /// Add algebraic constraint to FlatCvt
   pre::NodeRange AddAlgebraicConstraint(const AlgConPrepare& pr) {
-    pre::NodeRange nr;                                 // value presolve link
+    pre::NodeRange nr;                            // presolve bridge
     if (pr.qt.empty()) {
       if (pr.compl_var<0)
         nr = AddConstraint( LinConRange{ std::move(pr.lt),
@@ -263,15 +259,13 @@ class ProblemFlattener :
     return nr;
   }
 
-  /// Add a copy link from a source item
-  void AddCopyLinkFromSource(pre::NodeRange nr) {
-    GetCopyLink().AddEntry( {
-            GetValuePresolver().GetSourceNodes().GetConValues()(0).Add(),
+  void AddCopyBridgeFromSource(pre::NodeRange nr) {
+    GetCopyBridge().AddEntry( {
+            GetPresolver().GetSourceNodes().GetConValues()(0).Add(),
             nr
           } );
   }
 
-  /// Convert a logical constraint
   void ConvertLogicalCon(int i) {
     auto e = GetModel().logical_con(i);
     const auto resvar = MP_DISPATCH( Convert2Var(e.expr()) );
@@ -279,7 +273,7 @@ class ProblemFlattener :
     assert(GetFlatCvt().HasInitExpression(resvar));
     const auto& ie = GetFlatCvt().GetInitExpression(resvar);
     /// TODO check that logical cons' values come after algebraic ones
-    AddCopyLinkFromSource(
+    AddCopyBridgeFromSource(
           ie.GetCK()->GetValueNode().Select( ie.GetIndex() ));
   }
 
@@ -633,7 +627,7 @@ class ProblemFlattener :
     return VisitFunctionalExpression<TanConstraint>({ e.arg() });
   }
 
-  /// TODO how to link them if they are no real items in NL?
+  /// TODO how to bridge them if they are no real items in NL?
   void ConvertSOSConstraints() {
     if (sos()) {
       auto sosno = GetModel().
@@ -743,8 +737,7 @@ class ProblemFlattener :
   //////////////////////////// UTILITIES /////////////////////////////////
   ///
 protected:
-  pre::ValuePresolver& GetValuePresolver()
-  { return GetFlatCvt().GetValuePresolver(); }
+  pre::Presolver& GetPresolver() { return GetFlatCvt().GetPresolver(); }
 
 private:
   std::unordered_map<double, int> map_fixed_vars_;
@@ -757,8 +750,8 @@ class ProblemFlattener :
   int MakeFixedVar(double value) // TODO use proper const term in obj
   { return GetFlatCvt().MakeFixedVar(value); }
 
-  /// Presolve link just copying values between model items
-  pre::CopyLink& GetCopyLink() { return GetFlatCvt().GetCopyLink(); }
+  /// Presolve bridge copying values between model items
+  pre::CopyBridge& GetCopyBridge() { return GetFlatCvt().GetCopyBridge(); }
 
   ///////////////////////////////////////////////////////////////////////
   /////////////////////// OPTIONS /////////////////////////
diff --git a/include/mp/flat/redef/MIP/abs.h b/include/mp/flat/redef/MIP/abs.h
index e352b66d5..1dfb25e89 100644
--- a/include/mp/flat/redef/MIP/abs.h
+++ b/include/mp/flat/redef/MIP/abs.h
@@ -2,7 +2,7 @@
 #define ABS_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/alldiff.h b/include/mp/flat/redef/MIP/alldiff.h
index c08d98330..3a8a0a2d1 100644
--- a/include/mp/flat/redef/MIP/alldiff.h
+++ b/include/mp/flat/redef/MIP/alldiff.h
@@ -6,7 +6,7 @@
  */
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
@@ -25,7 +25,7 @@ class AllDiffConverter_MIP :
   using ItemType = AllDiffConstraint;
 
   /// Convert in positive context
-  /// TODO add presolve link?
+  /// TODO add presolve bridge?
   void ConvertCtxPos(const ItemType& alld, int ) {
     const auto& args = alld.GetArguments();
     const auto lba_dbl = GetMC().lb_array(args);
diff --git a/include/mp/flat/redef/MIP/complement.h b/include/mp/flat/redef/MIP/complement.h
index a8335f250..4c901bcaa 100644
--- a/include/mp/flat/redef/MIP/complement.h
+++ b/include/mp/flat/redef/MIP/complement.h
@@ -4,7 +4,7 @@
 #include <cmath>
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/cond_eq.h b/include/mp/flat/redef/MIP/cond_eq.h
index 1b3f95f1c..179a3d081 100644
--- a/include/mp/flat/redef/MIP/cond_eq.h
+++ b/include/mp/flat/redef/MIP/cond_eq.h
@@ -2,7 +2,7 @@
 #define COND_EQ_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/cond_ineq.h b/include/mp/flat/redef/MIP/cond_ineq.h
index 78e2d51ca..88211a515 100644
--- a/include/mp/flat/redef/MIP/cond_ineq.h
+++ b/include/mp/flat/redef/MIP/cond_ineq.h
@@ -2,7 +2,7 @@
 #define COND_INEQ_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/count.h b/include/mp/flat/redef/MIP/count.h
index 6aed9aad4..5f3bc2c80 100644
--- a/include/mp/flat/redef/MIP/count.h
+++ b/include/mp/flat/redef/MIP/count.h
@@ -2,7 +2,7 @@
 #define COUNT_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/div.h b/include/mp/flat/redef/MIP/div.h
index 501d29b32..f641b97b3 100644
--- a/include/mp/flat/redef/MIP/div.h
+++ b/include/mp/flat/redef/MIP/div.h
@@ -2,7 +2,7 @@
 #define DIV_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/ifthenelse.h b/include/mp/flat/redef/MIP/ifthenelse.h
index cbd7b9bc9..7bdf1933a 100644
--- a/include/mp/flat/redef/MIP/ifthenelse.h
+++ b/include/mp/flat/redef/MIP/ifthenelse.h
@@ -2,7 +2,7 @@
 #define IFTHENELSE_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/indicator_ge.h b/include/mp/flat/redef/MIP/indicator_ge.h
index 4b72769fe..dab1f9dad 100644
--- a/include/mp/flat/redef/MIP/indicator_ge.h
+++ b/include/mp/flat/redef/MIP/indicator_ge.h
@@ -2,7 +2,7 @@
 #define INDICATOR_GE_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/indicator_le.h b/include/mp/flat/redef/MIP/indicator_le.h
index f751a44ee..3aa8a33c9 100644
--- a/include/mp/flat/redef/MIP/indicator_le.h
+++ b/include/mp/flat/redef/MIP/indicator_le.h
@@ -2,7 +2,7 @@
 #define INDICATOR_LE_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/indicator_quad.h b/include/mp/flat/redef/MIP/indicator_quad.h
index 8525364c4..b1ec3d65c 100644
--- a/include/mp/flat/redef/MIP/indicator_quad.h
+++ b/include/mp/flat/redef/MIP/indicator_quad.h
@@ -6,7 +6,7 @@
   */
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/logical_and.h b/include/mp/flat/redef/MIP/logical_and.h
index f08d649d4..6eab87f01 100644
--- a/include/mp/flat/redef/MIP/logical_and.h
+++ b/include/mp/flat/redef/MIP/logical_and.h
@@ -2,7 +2,7 @@
 #define LOGICAL_AND_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/logical_not.h b/include/mp/flat/redef/MIP/logical_not.h
index 2acac9029..f92cc6b47 100644
--- a/include/mp/flat/redef/MIP/logical_not.h
+++ b/include/mp/flat/redef/MIP/logical_not.h
@@ -2,7 +2,7 @@
 #define LOGICAL_NOT_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/logical_or.h b/include/mp/flat/redef/MIP/logical_or.h
index 3380e8064..4ecf41774 100644
--- a/include/mp/flat/redef/MIP/logical_or.h
+++ b/include/mp/flat/redef/MIP/logical_or.h
@@ -2,7 +2,7 @@
 #define LOGICAL_OR_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/min_max.h b/include/mp/flat/redef/MIP/min_max.h
index 92efaeb04..41cecaa5f 100644
--- a/include/mp/flat/redef/MIP/min_max.h
+++ b/include/mp/flat/redef/MIP/min_max.h
@@ -6,7 +6,7 @@
  */
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/numberof_const.h b/include/mp/flat/redef/MIP/numberof_const.h
index 3c18b3dbd..503cde945 100644
--- a/include/mp/flat/redef/MIP/numberof_const.h
+++ b/include/mp/flat/redef/MIP/numberof_const.h
@@ -2,7 +2,7 @@
 #define NUMBEROF_CONST_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/MIP/numberof_var.h b/include/mp/flat/redef/MIP/numberof_var.h
index 3b8cea148..fd3fe3d69 100644
--- a/include/mp/flat/redef/MIP/numberof_var.h
+++ b/include/mp/flat/redef/MIP/numberof_var.h
@@ -2,7 +2,7 @@
 #define NUMBEROF_VAR_H
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/include/mp/flat/redef/redef_base.h b/include/mp/flat/redef/redef_base.h
index cc05a53f2..ac79a2c8a 100644
--- a/include/mp/flat/redef/redef_base.h
+++ b/include/mp/flat/redef/redef_base.h
@@ -2,7 +2,7 @@
 #define REDEF_BASE_H
 
 #include "mp/format.h"
-#include "mp/valcvt.h"
+#include "mp/presolve.h"
 
 namespace mp {
 
@@ -19,7 +19,7 @@ class BasicItemConverter {
   /// Access ModelConverter
   ModelConverter& GetMC() { return mdl_cvt_; }
   /// Access Presolver
-  pre::ValuePresolver& GetPre() { return GetMC().GetPresolver(); }
+  pre::Presolver& GetPre() { return GetMC().GetPresolver(); }
   /// Access specific item's ValueNode
   template <class Item>
   pre::ValueNode& GetVN(Item* pc)
@@ -47,9 +47,9 @@ class BasicFuncConstrCvt :
   /// if only one of these is necessary, significant model reduction
   /// can be achieved in certain cases.
   ///
-  /// Responsible for adding presolve links, if any
+  /// Responsible for adding presolve bridges, if any
   /// @param item: the item to be converted
-  /// @param i: item index, used to create a presolve link
+  /// @param i: item index, used to create a presolve bridge
   ///
   /// The Impl can reimplement this
   template <class ItemType>
diff --git a/include/mp/flat/redef/std/range_con.h b/include/mp/flat/redef/std/range_con.h
index f1d2f5f54..8f2fedd38 100644
--- a/include/mp/flat/redef/std/range_con.h
+++ b/include/mp/flat/redef/std/range_con.h
@@ -6,32 +6,32 @@
  */
 
 #include "mp/flat/redef/redef_base.h"
-#include "mp/valcvt-link.h"
-#include "mp/flat/constr_std.h"
+#include "mp/presolve-bridge.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
 namespace pre {
 
-/// Presolve link between RangeCon and Con(LE/EQ/GE)+Slack.
+/// Presolve bridge between RangeCon and Con(LE/EQ/GE)+Slack.
 /// TODO dependency inversion #164
-/// (FlatConverter needs just a BasicLink*? Entry type?)
+/// (FlatConverter needs just a BasicBridge*? Entry type?)
 template <class ModelConverter, class RangeCon>
 class RangeCon2Slack :
-    public BasicStaticIndivEntryLink<
+    public BasicStaticIndivEntryBridge<
       RangeCon2Slack<ModelConverter, RangeCon>, 3, 3> {
 public:
   /// Base class
-  using Base = BasicStaticIndivEntryLink<
+  using Base = BasicStaticIndivEntryBridge<
     RangeCon2Slack<ModelConverter, RangeCon>, 3, 3>;
 
   /// Constructor
   RangeCon2Slack(ModelConverter& cvt,
                               const typename Base::NodeList& ndl) :
-    Base(cvt.GetValuePresolver(), ndl), cvt_(cvt) { }
+    Base(cvt.GetPresolver(), ndl), cvt_(cvt) { }
 
-  /// Define pre- / postsolve methods for individual link entries.
-  /// Typedef LinkEntry is created in Base as std::array<int, 3>
+  /// Define pre- / postsolve methods for individual bridge entries.
+  /// Typedef BridgeEntry is created in Base as std::array<int, 3>
   /// (3 is the base class template parameter)
   /// and means the following indexes: {range_con, lin_con, slack_index}
 
@@ -40,7 +40,7 @@ class RangeCon2Slack :
   /// Primals: compute slack.
   /// Slacks are probably only needed for Gurobi LP warmstart.
   /// Who does not need them, can use unpresolved primal solution.
-  void PresolveSolutionEntry(const typename Base::LinkEntry& be) {
+  void PresolveSolutionEntry(const typename Base::BridgeEntry& be) {
     SetDbl(be, 1, GetDbl(be, 0));
     const auto& orig_cons =
         GetMC().template GetConstraint<RangeCon>(be[0]);
@@ -48,7 +48,7 @@ class RangeCon2Slack :
   }
 
   /// Postsolve solution (primal + dual)
-  void PostsolveSolutionEntry(const typename Base::LinkEntry& be) {
+  void PostsolveSolutionEntry(const typename Base::BridgeEntry& be) {
     SetDbl(be, 0, GetDbl(be, 1));
   }
 
@@ -57,26 +57,26 @@ class RangeCon2Slack :
   /// From a range constraint's basis status,
   /// transfer it to the slack.
   /// Set the new constraint's status to 'equ'.
-  void PresolveBasisEntry(const typename Base::LinkEntry& be) {
+  void PresolveBasisEntry(const typename Base::BridgeEntry& be) {
     SetInt(be, 2, GetInt(be, 0));
     SetInt(be, 1, (int)BasicStatus::equ);
   }
   /// Postsolve basis
   ///
   /// The reverse (forget solver's constraint status)
-  void PostsolveBasisEntry(const typename Base::LinkEntry& be) {
+  void PostsolveBasisEntry(const typename Base::BridgeEntry& be) {
     SetInt(be, 0, GetInt(be, 2));
   }
 
   /// Presolve IIS
-  void PresolveIISEntry(const typename Base::LinkEntry& ) {
+  void PresolveIISEntry(const typename Base::BridgeEntry& ) {
     /// Should not need
   }
 
   /// Postsolve IIS
   ///
   /// Take slack's if set, otherwise the constraint's
-  void PostsolveIISEntry(const typename Base::LinkEntry& be) {
+  void PostsolveIISEntry(const typename Base::BridgeEntry& be) {
     if (auto slk_iis = GetInt(be, 2))
       SetInt(be, 0, slk_iis);
     else
@@ -84,11 +84,11 @@ class RangeCon2Slack :
   }
 
   /// Mark Lazy/user cut: copy flag
-  void PresolveLazyUserCutFlagsEntry(const typename Base::LinkEntry& be) {
+  void PresolveLazyUserCutFlagsEntry(const typename Base::BridgeEntry& be) {
     SetInt(be, 1, GetInt(be, 0));
   }
 
-  void PostsolveLazyUserCutFlagsEntry(const typename Base::LinkEntry& ) {
+  void PostsolveLazyUserCutFlagsEntry(const typename Base::BridgeEntry& ) {
     /// Should not need
   }
 
@@ -142,9 +142,9 @@ class RangeConstraintConverter :
 
   /// Conversion
   ///
-  /// Responsible for adding presolve links
+  /// Responsible for adding presolve bridges
   /// @param item: the item to be converted
-  /// @param i: item index, used to create a presolve link
+  /// @param i: item index, used to create a presolve bridge
   void Convert(const ItemType& item, int i) {
     auto rr = Relate(item.lb(), item.ub());
     if (rr[0] && rr[1] && rr[2])
@@ -165,7 +165,7 @@ class RangeConstraintConverter :
     body.add_term(1.0, slk);
     AlgConEQ lceq { std::move(body), item.ub() };
     int i1 = GetMC().AddConstraint(std::move(lceq));
-    GetSlackLink().AddEntry({i, i1, slk});
+    GetSlackBridge().AddEntry({i, i1, slk});
   }
   void ConvertWithRhs(const ItemType& item, int i, RangeRelations rr) {
     pre::NodeRange nr;              // target node+index
@@ -181,15 +181,15 @@ class RangeConstraintConverter :
             AlgConEQ( item.GetBody(),
                       (item.lb()+item.ub()) / 2.0 ) );
     } // else, both are inf, forget
-    GetMC().GetCopyLink().AddEntry(
+    GetMC().GetCopyBridge().AddEntry(
           { GET_CONSTRAINT_VALUE_NODE(ItemType).Select(i), nr });
   }
 
-  using SlackLink = pre::RangeLinCon2Slack<ModelConverter>;
-  SlackLink& GetSlackLink() { return link_rng2slk_; }
+  using SlackBridge = pre::RangeLinCon2Slack<ModelConverter>;
+  SlackBridge& GetSlackBridge() { return bridge_rng2slk_; }
 
 private:
-  SlackLink link_rng2slk_ {
+  SlackBridge bridge_rng2slk_ {
     GetMC(), {
           &GET_CONSTRAINT_VALUE_NODE(ItemType),
           &GET_CONSTRAINT_VALUE_NODE(AlgConEQ),
diff --git a/include/mp/model-mgr-base.h b/include/mp/model-mgr-base.h
index 6f59eb179..248098bc6 100644
--- a/include/mp/model-mgr-base.h
+++ b/include/mp/model-mgr-base.h
@@ -32,7 +32,8 @@ class BasicModelManager {
   /// Read NL model
   virtual void ReadNLModel(const std::string& nl_filename,
                            const std::string& filename_no_ext,
-                           void (*cb_checkmodel)(size_t, size_t, size_t)) = 0;
+                           std::function<void (size_t, size_t, size_t)>
+                             cb_checkmodel) = 0;
 
   /// User-provided primal solution
   virtual ArrayRef<double> InitialValues() = 0;
diff --git a/include/mp/model-mgr-with-pb.h b/include/mp/model-mgr-with-pb.h
index 798242f65..fb1848400 100644
--- a/include/mp/model-mgr-with-pb.h
+++ b/include/mp/model-mgr-with-pb.h
@@ -86,8 +86,8 @@ class ModelManagerWithProblemBuilder :
 
   void ReadNLModel(const std::string& nl_filename,
                    const std::string& filename_no_ext,
-                   void (*cb_checkmodel)(size_t, size_t, size_t))
-  override {
+                   std::function<void (size_t, size_t, size_t)>
+                     cb_checkmodel) override {
     steady_clock::time_point start = steady_clock::now();
 
     ReadNLFile(nl_filename);
diff --git a/include/mp/valcvt-base.h b/include/mp/presolve-base.h
similarity index 89%
rename from include/mp/valcvt-base.h
rename to include/mp/presolve-base.h
index 21da43116..72c5d35f0 100644
--- a/include/mp/valcvt-base.h
+++ b/include/mp/presolve-base.h
@@ -1,8 +1,9 @@
-#ifndef VALUE_PRESOLVE_BASE_H
-#define VALUE_PRESOLVE_BASE_H
+#ifndef PRESOLVE_BASE_H
+#define PRESOLVE_BASE_H
 
 /**
-  Interface for value presolver:
+  Interface for value presolver: transforms solutions etc.
+  between original and presolved model
   */
 
 #include <map>
@@ -13,10 +14,6 @@
 
 namespace mp {
 
-
-/// Namespace mp::pre: value presolve methods.
-/// They transform solutions, etc.,
-/// between the original and presolved models
 namespace pre {
 
 /// Debugging template
@@ -182,12 +179,12 @@ using ModelValuesInt = ModelValues< ValueMapInt >;
 using ModelValuesDbl = ModelValues< ValueMapDbl >;
 
 
-/// ValuePresolver interface.
-/// Addresses value pre- / postsolve (solutions, basis, etc)
-class BasicValuePresolver {
+/// Presolver interface
+/// Currently only addresses value pre- / postsolve (solutions, basis, ...)
+class BasicPresolver {
 public:
   /// Virtual destructor
-  virtual ~BasicValuePresolver() = default;
+  virtual ~BasicPresolver() = default;
 
   /// Presolve solution (primal + dual)
   virtual ModelValuesDbl PresolveSolution(const ModelValuesDbl& ) = 0;
@@ -209,7 +206,7 @@ class BasicValuePresolver {
 };
 
 
-/// index range for some link or node
+/// index range for some bridge or node
 struct IndexRange {
   /// Construct, possibly from a single index
   IndexRange(int b=0, int e=-1) : beg(b), end(e<0 ? b+1 : e) { }
@@ -234,22 +231,22 @@ struct IndexRange {
 
 /// Some backends need presolver
 /// for pre- / postsolving of suffix values etc
-class BasicValuePresolverKeeper {
+class BasicPresolverKeeper {
 protected:
-  void SetValuePresolver(pre::BasicValuePresolver* pPre) {
+  void SetPresolver(pre::BasicPresolver* pPre) {
     pPresolver_ = pPre;
   }
 
-  const pre::BasicValuePresolver& GetValuePresolver() const
+  const pre::BasicPresolver& GetPresolver() const
   { assert(pPresolver_); return *pPresolver_; }
-  pre::BasicValuePresolver& GetValuePresolver()
+  pre::BasicPresolver& GetPresolver()
   { assert(pPresolver_); return *pPresolver_; }
 
 
 private:
-  pre::BasicValuePresolver* pPresolver_ = nullptr;
+  pre::BasicPresolver* pPresolver_ = nullptr;
 };
 
 } // namespace mp
 
-#endif // VALUE_PRESOLVE_BASE_H
+#endif // PRESOLVE_BASE_H
diff --git a/include/mp/valcvt-link.h b/include/mp/presolve-bridge.h
similarity index 52%
rename from include/mp/valcvt-link.h
rename to include/mp/presolve-bridge.h
index 5e519721d..f70507b65 100644
--- a/include/mp/valcvt-link.h
+++ b/include/mp/presolve-bridge.h
@@ -1,25 +1,25 @@
-#ifndef VALUE_PRESOLVE_LINK_H
-#define VALUE_PRESOLVE_LINK_H
+#ifndef PRESOLVE_BRIDGE_H
+#define PRESOLVE_BRIDGE_H
 
 #include <vector>
 #include <array>
 
 #include "mp/common.h"
-#include "valcvt-node.h"
+#include "presolve-node.h"
 
 
 namespace mp {
 
 namespace pre {
 
-/// Index range in a link
-using ValcvtLinkIndexRange = IndexRange;
+/// Index range in a bridge
+using BridgeIndexRange = IndexRange;
 
-/// Declare ValuePresolver
-class ValuePresolver;
+/// Declare Presolver
+class Presolver;
 
 /// Macro for a list of pre- / postsolve method definitions
-/// in a link.
+/// in a bridge.
 /// Requires PRESOLVE_KIND defined to declare / define corr. methods
 #define LIST_PRESOLVE_METHODS \
   PRESOLVE_KIND(Solution) \
@@ -28,53 +28,49 @@ class ValuePresolver;
   PRESOLVE_KIND(LazyUserCutFlags)
 // ...
 
-
-/// ValuePresolveLink interface
+/// Bridge interface
 ///
-/// A link is an array of value converters between nodes.
+/// A bridge is an array of value converters between nodes.
 /// All converters are of the same type
-class BasicValcvtLink {
+class BasicBridge {
 public:
   /// Constructor
-  BasicValcvtLink(ValuePresolver& pre) : vsalue_presolver_(pre) { }
+  BasicBridge(Presolver& pre) : presolver_(pre) { }
   /// Virtual destructor
-  virtual ~BasicValcvtLink() = default;
+  virtual ~BasicBridge() = default;
 
-  /// The below pre- / postsolve methods
-  /// work on a range of link entries
+  /// The below pre- / postsolves work on a range of bridge entries
   /// Postsolves should usually loop the range backwards
 
 #define PRESOLVE_KIND(name) \
-  virtual void Presolve ## name (ValcvtLinkIndexRange ) = 0; \
-  virtual void Postsolve ## name(ValcvtLinkIndexRange ) = 0;
+  virtual void Presolve ## name (BridgeIndexRange ) = 0; \
+  virtual void Postsolve ## name(BridgeIndexRange ) = 0;
 
   LIST_PRESOLVE_METHODS
 
 protected:
-  /// Add a range of link entries to the Presolver's list.
-  /// Every derived link should call either of the next two methods
-  /// whenever adding a link entry.
-  /// Version 1: add single link
-  void RegisterLinkIndex(int i)
-  { RegisterLinkIndexRange( {i, i+1} ); }
-  /// Version 2: add a range of links
-  void RegisterLinkIndexRange(ValcvtLinkIndexRange );
+  /// Add a range of bridge entries to the Presolver's list
+  /// Every derived bridge should call either of the next two
+  /// whenever adding a bridge entry
+  void RegisterBridgeIndex(int i)
+  { RegisterBridgeIndexRange( {i, i+1} ); }
+  void RegisterBridgeIndexRange(BridgeIndexRange );
 
 private:
-  ValuePresolver& vsalue_presolver_;
+  Presolver& presolver_;
 };
 
 
-/// Link range: range of conversion specifiers of certain type.
-/// The link is specified as well
-struct LinkRange {
+/// Bridge range: range of conversion specifiers of certain type
+/// The bridge is specified as well
+struct BridgeRange {
   /// Try & extend the range
   /// @return true iff extension worked,
   /// otherwise the caller would have to add the new range
   /// separately
-  bool ExtendRange(LinkRange br) {
-    if (&b_ == &br.b_) {                  // same link?
-      if (ir_.end == br.ir_.beg) {        // and consecutive ranges?
+  bool ExtendRange(BridgeRange br) {
+    if (&b_ == &br.b_) {                  // same bridge
+      if (ir_.end == br.ir_.beg) {        // and consecutive ranges
         ir_.end = br.ir_.end;
         return true;
       }
@@ -82,35 +78,35 @@ struct LinkRange {
     return false;
   }
 
-  BasicValcvtLink& b_;
-  ValcvtLinkIndexRange ir_;
+  BasicBridge& b_;
+  BridgeIndexRange ir_;
 };
 
 
-/// A specific link: each entry just copies a range of values/
+/// A specific bridge: each entry just copies a range of values
 /// Useful to transfer values between NL and internal model,
 /// internal model and solver, and in conversions preserving
 /// all values
-class CopyLink : public BasicValcvtLink {
+class CopyBridge : public BasicBridge {
 public:
   /// Constructor
-  CopyLink(ValuePresolver& pre) : BasicValcvtLink(pre) { }
+  CopyBridge(Presolver& pre) : BasicBridge(pre) { }
 
-  /// Single link entry
-  using LinkEntry = std::pair<NodeRange, NodeRange>;
+  /// Single bridge entry
+  using BridgeEntry = std::pair<NodeRange, NodeRange>;
 
   /// Collection of entries
-  using CollectionOfEntries = std::vector<LinkEntry>;
+  using CollectionOfEntries = std::vector<BridgeEntry>;
 
   /// Add entry
   /// Instead of a new entry, tries to extend the last one
   /// if exists
-  void AddEntry(LinkEntry be) {
+  void AddEntry(BridgeEntry be) {
     if (entries_.empty() ||
         !entries_.back().first.ExtendableBy(be.first) ||
         !entries_.back().second.ExtendableBy(be.second)) {
       entries_.push_back(be);             // Add new entry
-      RegisterLinkIndex(entries_.size()-1);
+      RegisterBridgeIndex(entries_.size()-1);
     } else {                              // Extend last entry
       entries_.back().first.ExtendBy(be.first);
       entries_.back().second.ExtendBy(be.second);
@@ -122,23 +118,23 @@ class CopyLink : public BasicValcvtLink {
 
 #undef PRESOLVE_KIND
 #define PRESOLVE_KIND(name) \
-  void Presolve ## name (ValcvtLinkIndexRange ir) override \
+  void Presolve ## name (BridgeIndexRange ir) override \
   { CopySrcDest(ir); } \
-  void Postsolve ## name(ValcvtLinkIndexRange ir) override \
+  void Postsolve ## name(BridgeIndexRange ir) override \
   { CopyDestSrc(ir); }
 
   LIST_PRESOLVE_METHODS
 
 protected:
   /// Copy src -> dest for index range ir
-  void CopySrcDest(ValcvtLinkIndexRange ir) {
+  void CopySrcDest(BridgeIndexRange ir) {
     for (int i=ir.beg; i!=ir.end; ++i) {
       const auto& br = entries_[i];
       Copy(br.first, br.second);
     }
   }
   /// Copy src <- dest for index range ir. Loop backwards
-  void CopyDestSrc(ValcvtLinkIndexRange ir) {
+  void CopyDestSrc(BridgeIndexRange ir) {
     for (int i=ir.end; (i--)!=ir.beg; ) {
       const auto& br = entries_[i];
       Copy(br.second, br.first);
@@ -150,42 +146,40 @@ class CopyLink : public BasicValcvtLink {
 };
 
 
-/// A stub for links which process each entry individually,
-/// in contrast to Presolve...(ValcvtLinkIndexRange ...).
-/// Some of such links could be optimized to store
+/// A stub for bridges which process each entry individually,
+/// in contrast to Presolve...(BridgeIndexRange ...)
+/// Some of such bridges could be optimized to store
 /// a range of transformations in each entry if that helps
-/// (but this could be an overoptimization?)
-///
-/// Usage: a derived class should define some methods
-/// Presolve...(const LinkEntry& ) and Postsolve...(const LinkEntry&).
 ///
-/// TODO: we could default as follows:
-/// Those methods which are not defined, just copy values
+/// Usage: a derived class should define types
+/// BridgeEntry and NodeList, and some methods
+/// Presolve...(const BridgeEntry& ) and Postsolve...(const BridgeEntry&).
+/// TODO: Those methods which are not defined, just copy values
 /// (which might be correct in _some_ cases).
-/// Then, need a "default copy" method.
+/// Need a "default copy" method.
 ///
 /// Using CRTP: https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern
-template <class Impl, class LinkEntry>
-class BasicIndivEntryLink : public BasicValcvtLink {
+template <class Impl, class BridgeEntry>
+class BasicIndivEntryBridge : public BasicBridge {
 public:
   /// Constructor
-  BasicIndivEntryLink(ValuePresolver& pre) :
-    BasicValcvtLink(pre) { }
+  BasicIndivEntryBridge(Presolver& pre) :
+    BasicBridge(pre) { }
 
   /// Add entry
   /// Instead of a new entry, tries to extend the last one
   /// if exists
-  void AddEntry(LinkEntry be) {
+  void AddEntry(BridgeEntry be) {
     entries_.push_back(be);             // Add new entry
-    RegisterLinkIndex(entries_.size()-1);
+    RegisterBridgeIndex(entries_.size()-1);
   }
 
 #undef PRESOLVE_KIND
 #define PRESOLVE_KIND(name) \
-  void Presolve ## name (ValcvtLinkIndexRange ir) override { \
+  void Presolve ## name (BridgeIndexRange ir) override { \
     for (int i=ir.beg; i!=ir.end; ++i) \
       MPD( Presolve ## name ## Entry(entries_.at(i)) ); } \
-  void Postsolve ## name(ValcvtLinkIndexRange ir) override { \
+  void Postsolve ## name(BridgeIndexRange ir) override { \
     for (int i=ir.end; i--!=ir.beg; ) \
       MPD( Postsolve ## name ## Entry(entries_.at(i)) ); }
 
@@ -193,26 +187,26 @@ class BasicIndivEntryLink : public BasicValcvtLink {
 
 
 private:
-  std::vector<LinkEntry> entries_;
+  std::vector<BridgeEntry> entries_;
 };
 
 
-/// A static indiv entry link has a fixed number of ValueNodes
+/// A static indiv entry bridge has a fixed number of ValueNodes
 /// and indexes into them.
 /// Generally NNodes==NIndexes
 template <class Impl, int NNodes, int NIndexes>
-class BasicStaticIndivEntryLink :
-    public BasicIndivEntryLink<Impl, std::array<int, NIndexes> > {
+class BasicStaticIndivEntryBridge :
+    public BasicIndivEntryBridge<Impl, std::array<int, NIndexes> > {
 public:
   /// Base class
-  using Base = BasicIndivEntryLink<Impl, std::array<int, NIndexes> >;
+  using Base = BasicIndivEntryBridge<Impl, std::array<int, NIndexes> >;
   /// Typedef NodeList
   using NodeList = std::array<ValueNode*, NNodes>;
-  /// Typedef: LinkEntry is just an array if node indexes
-  using LinkEntry = std::array<int, NIndexes>;
+  /// Typedef: BridgeEntry is just an array if node indexes
+  using BridgeEntry = std::array<int, NIndexes>;
 
   /// Constructor
-  BasicStaticIndivEntryLink(ValuePresolver& pre, const NodeList& ndl) :
+  BasicStaticIndivEntryBridge(Presolver& pre, const NodeList& ndl) :
     Base(pre), ndl_(ndl) { }
 
 protected:
@@ -224,23 +218,23 @@ class BasicStaticIndivEntryLink :
   /// Access int value at the node \a pos at the index
   /// stored in \a be[pos]
   ///
-  /// @param be: a LinkEntry
+  /// @param be: a BridgeEntry
   /// @param pos: node number from 0..NNodes-1
-  int GetInt(const LinkEntry& be, size_t pos) const
+  int GetInt(const BridgeEntry& be, size_t pos) const
   { return GetNode(pos).GetInt(be[pos]); }
   /// SetInt
-  void SetInt(const LinkEntry& be, size_t pos, int i)
+  void SetInt(const BridgeEntry& be, size_t pos, int i)
   { GetNode(pos).SetInt(be[pos], i); }
 
   /// Access double value at the node \a pos at the index
   /// stored in \a be[pos]
   ///
-  /// @param be: a LinkEntry
+  /// @param be: a BridgeEntry
   /// @param pos: node number from 0..NNodes-1
-  double GetDbl(const LinkEntry& be, size_t pos) const
+  double GetDbl(const BridgeEntry& be, size_t pos) const
   { return GetNode(pos).GetDbl(be[pos]); }
   /// SetDbl
-  void SetDbl(const LinkEntry& be, size_t pos, double i)
+  void SetDbl(const BridgeEntry& be, size_t pos, double i)
   { GetNode(pos).SetDbl(be[pos], i); }
 
 private:
@@ -251,4 +245,4 @@ class BasicStaticIndivEntryLink :
 
 } // namespace mp
 
-#endif // VALUE_PRESOLVE_LINK_H
+#endif // PRESOLVE_BRIDGE_H
diff --git a/include/mp/valcvt-node.h b/include/mp/presolve-node.h
similarity index 95%
rename from include/mp/valcvt-node.h
rename to include/mp/presolve-node.h
index bffdcd3ab..daeaa0c4f 100644
--- a/include/mp/valcvt-node.h
+++ b/include/mp/presolve-node.h
@@ -1,7 +1,7 @@
-#ifndef VALUE_PRESOLVE_NODE_H
-#define VALUE_PRESOLVE_NODE_H
+#ifndef PRESOLVE_NODE_H
+#define PRESOLVE_NODE_H
 
-#include "valcvt-base.h"
+#include "presolve-base.h"
 
 
 namespace mp {
@@ -71,7 +71,7 @@ class ValueNode {
   /// Constructor
   ValueNode(std::string nm) : name_(nm) { }
 
-  /// Declared size (what is being used by links)
+  /// Declared size (what is being used by bridges)
   size_t size() const { return sz_; }
 
   /// Create entry (range) pointer: add n elements
@@ -95,7 +95,7 @@ class ValueNode {
 
   /// Assign from ArrayRef<int>. Always copy the values.
   /// TODO Check that values fit the declared size?
-  /// Problematic since, e.g., Gurobi adds more variables in feasrelax
+  /// Problematic since e.g. Gurobi adds more variables in feasrelax
   ValueNode& operator=(std::vector<int> ai)
   {
     // assert(ai.size() <= size());
@@ -206,4 +206,4 @@ using ModelValuesTerminal = ModelValues< NodeMap >;
 } // namespace mp
 
 
-#endif // VALUE_PRESOLVE_NODE_H
+#endif // PRESOLVE_NODE_H
diff --git a/include/mp/valcvt.h b/include/mp/presolve.h
similarity index 61%
rename from include/mp/valcvt.h
rename to include/mp/presolve.h
index b7f13321e..8d2b933d5 100644
--- a/include/mp/valcvt.h
+++ b/include/mp/presolve.h
@@ -1,15 +1,15 @@
-#ifndef VALUE_PRESOLVE_H
-#define VALUE_PRESOLVE_H
+#ifndef PRESOLVE_H
+#define PRESOLVE_H
 
 /**
-  @file valcvt.h.
+  @file presolve.h
   Implementation of value presolver
   */
 
 #include <deque>
 
-#include "valcvt-node.h"
-#include "valcvt-link.h"
+#include "presolve-node.h"
+#include "presolve-bridge.h"
 
 
 namespace mp {
@@ -17,17 +17,17 @@ namespace mp {
 namespace pre {
 
 
-/// Array of link ranges
+/// Array of bridge ranges
 ///
 /// This defines a chain of transformations
-class LinkRangeList : private std::deque<LinkRange> {
+class BridgeRangeList : private std::deque<BridgeRange> {
 public:
   /// Base class typedef
-  using Base = std::deque<LinkRange>;
+  using Base = std::deque<BridgeRange>;
 
   /// Add another range to the list,
   /// tries to extend the last range if possible
-  void Add(LinkRange br) {
+  void Add(BridgeRange br) {
     if (empty() || !back().ExtendRange(br))
       push_back(br);
   }
@@ -49,10 +49,8 @@ class LinkRangeList : private std::deque<LinkRange> {
 };
 
 
-/// Value presolver implementation.
-/// A ValuePresolver converts solutions and suffixes
-/// between the original model and the presolved one.
-class ValuePresolver : public BasicValuePresolver {
+/// Value presolver implementation
+class Presolver : public BasicPresolver {
 public:
   /// Source nodes for model items
   const ModelValuesTerminal& GetSourceNodes() const { return src_; }
@@ -62,43 +60,43 @@ class ValuePresolver : public BasicValuePresolver {
   const ModelValuesTerminal& GetTargetNodes() const { return dest_; }
   ModelValuesTerminal& GetTargetNodes() { return dest_; }
 
-  /// Add (register) a link range
-  /// This is normally called automatically from a link
+  /// Add (register) a bridge range
+  /// This is normally called automatically from a bridge
   /// when an entry is added
-  void Add(LinkRange br) { brl_.Add(br); }
+  void Add(BridgeRange br) { brl_.Add(br); }
 
   /// Presolve solution (primal + dual)
   ModelValuesDbl PresolveSolution(const ModelValuesDbl& mvd) override
-  { return RunPresolve(&BasicValcvtLink::PresolveSolution, mvd); }
+  { return RunPresolve(&BasicBridge::PresolveSolution, mvd); }
   /// Postsolve solution (primal + dual)
   ModelValuesDbl PostsolveSolution(const ModelValuesDbl& mvd) override
-  { return RunPostsolve(&BasicValcvtLink::PostsolveSolution, mvd); }
+  { return RunPostsolve(&BasicBridge::PostsolveSolution, mvd); }
 
   /// Presolve basis (vars + cons)
   ModelValuesInt PresolveBasis(const ModelValuesInt& mvi) override
-  { return RunPresolve(&BasicValcvtLink::PresolveBasis, mvi); }
+  { return RunPresolve(&BasicBridge::PresolveBasis, mvi); }
   /// Postsolve solution (vars + cons)
   ModelValuesInt PostsolveBasis(const ModelValuesInt& mvi) override
-  { return RunPostsolve(&BasicValcvtLink::PostsolveBasis, mvi); }
+  { return RunPostsolve(&BasicBridge::PostsolveBasis, mvi); }
 
   /// Presolve IIS (vars + cons)
   ModelValuesInt PresolveIIS(const ModelValuesInt& mvi) override
-  { return RunPresolve(&BasicValcvtLink::PresolveIIS, mvi); }
+  { return RunPresolve(&BasicBridge::PresolveIIS, mvi); }
   /// Postsolve IIS (vars + cons)
   ModelValuesInt PostsolveIIS(const ModelValuesInt& mvi) override
-  { return RunPostsolve(&BasicValcvtLink::PostsolveIIS, mvi); }
+  { return RunPostsolve(&BasicBridge::PostsolveIIS, mvi); }
 
   /// Presolve LazyUserCutFlags (vars + cons)
   ModelValuesInt PresolveLazyUserCutFlags(const ModelValuesInt& mvi) override
-  { return RunPresolve(&BasicValcvtLink::PresolveLazyUserCutFlags, mvi); }
+  { return RunPresolve(&BasicBridge::PresolveLazyUserCutFlags, mvi); }
 
 protected:
   /// Helper type: virtual member function pointer
-  using LinkFn = void (BasicValcvtLink::*)(ValcvtLinkIndexRange);
+  using BridgeFn = void (BasicBridge::*)(BridgeIndexRange);
 
   /// Generic value presolve loop: forward
   template <class ModelValues>
-  ModelValues RunPresolve(LinkFn fn, const ModelValues& mv) const {
+  ModelValues RunPresolve(BridgeFn fn, const ModelValues& mv) const {
     src_ = mv;
     for (const auto& br: brl_)
       (br.b_.*fn)(br.ir_);
@@ -107,7 +105,7 @@ class ValuePresolver : public BasicValuePresolver {
 
   /// Generic value postsolve loop: backward
   template <class ModelValues>
-  ModelValues RunPostsolve(LinkFn fn, const ModelValues& mv) const {
+  ModelValues RunPostsolve(BridgeFn fn, const ModelValues& mv) const {
     dest_ = mv;
     for (auto rit=brl_.rbegin(); rit!=brl_.rend(); ++rit)
       (rit->b_.*fn)(rit->ir_);
@@ -117,17 +115,17 @@ class ValuePresolver : public BasicValuePresolver {
 private:
   mutable ModelValuesTerminal src_{std::string("src")},
     dest_{std::string("dest")};
-  LinkRangeList brl_;
+  BridgeRangeList brl_;
 };
 
 
-/// Implement link range registration in global Presolver
+/// Implement bridge range registration in global Presolver
 inline void
-BasicValcvtLink::RegisterLinkIndexRange(ValcvtLinkIndexRange bir)
-{ vsalue_presolver_.Add( { *this, bir } ); }
+BasicBridge::RegisterBridgeIndexRange(BridgeIndexRange bir)
+{ presolver_.Add( { *this, bir } ); }
 
 } // namespace pre
 
 } // namespace mp
 
-#endif // VALUE_PRESOLVE_H
+#endif // PRESOLVE_H
diff --git a/solvers/CMakeLists.txt b/solvers/CMakeLists.txt
index 03cd93756..29f903533 100644
--- a/solvers/CMakeLists.txt
+++ b/solvers/CMakeLists.txt
@@ -233,10 +233,6 @@ add_ampl_backend(copt DLL_RUNTIME SHARED_LIB MODULE COPT LIBRARIES ${COPT_LIBS}
 add_ampl_backend(highsdirect DLL_RUNTIME SHARED_LIB
   MODULE HIGHS LIBRARIES ${HIGHS_LIBS} ${CMAKE_DL_LIBS})
 
-
-add_ampl_backend(ortoolsmp DLL_RUNTIME SHARED_LIB
-  MODULE ortoolsmp LIBRARIES ${ortoolsmp_LIBS} ${CMAKE_DL_LIBS})
-
 ## TODO Cannot use 'add_ampl_backend' because of the -direct name suffix
 add_ampl_solver(cplexdirect DLL_RUNTIME SHARED_LIB MODULE CPLEX
   cplex-ampls-c-api.h
diff --git a/solvers/copt/copt-lib.c b/solvers/copt/copt-lib.c
index fec59fdca..c5ec1031d 100644
--- a/solvers/copt/copt-lib.c
+++ b/solvers/copt/copt-lib.c
@@ -17,9 +17,9 @@ APIEXPORT copt_prob* AMPLloadmodel(int argc, char** argv, void** slvout) {
 }
 
 APIEXPORT void AMPLwritesolution(AMPLS_MP_Solver* slv) {
-  AMPLSReportResults(slv);
+  AMPLSReportResults(&slv);
 }
 
 APIEXPORT void AMPLclosesolver(AMPLS_MP_Solver* slv) {
-  AMPLSCloseCopt(slv);
+  AMPLSCloseCopt(&slv);
 }
\ No newline at end of file
diff --git a/solvers/copt/coptbackend.cc b/solvers/copt/coptbackend.cc
index b9cf10df3..59f955bb3 100644
--- a/solvers/copt/coptbackend.cc
+++ b/solvers/copt/coptbackend.cc
@@ -34,12 +34,12 @@ namespace mp {
 /// need it to convert solution data
 /// @return CoptModelMgr
 std::unique_ptr<BasicModelManager>
-CreateCoptModelMgr(CoptCommon&, Env&, pre::BasicValuePresolver*&);
+CreateCoptModelMgr(CoptCommon&, Env&, pre::BasicPresolver*&);
 
 
 void CoptBackend::OpenSolver() {
   int status = 0;
-  const auto create_fn = GetCallbacks().init;
+  const auto& create_fn = GetCallbacks().cb_initsolver_;
   if (create_fn)
     set_env((copt_env*)create_fn());
   else
@@ -71,10 +71,10 @@ void CoptBackend::CloseSolver() {
 
 CoptBackend::CoptBackend() {
   /// Create a ModelManager
-  pre::BasicValuePresolver* pPre;
+  pre::BasicPresolver* pPre;
   auto data = CreateCoptModelMgr(*this, *this, pPre);
   SetMM( std::move( data ) );
-  SetValuePresolver(pPre);
+  SetPresolver(pPre);
 }
 
 CoptBackend::~CoptBackend() {
@@ -102,7 +102,7 @@ void CoptBackend::InitOptionParsing() {
 }
 
 Solution CoptBackend::GetSolution() {
-  auto mv = GetValuePresolver().PostsolveSolution(
+  auto mv = GetPresolver().PostsolveSolution(
         { PrimalSolution(), DualSolution() } );
   return { mv.GetVarValues()(), mv.GetConValues()(),
     GetObjectiveValues() };   // TODO postsolve obj values
@@ -632,7 +632,7 @@ SolutionBasis CoptBackend::GetBasis() {
   std::vector<int> varstt = VarStatii();
   std::vector<int> constt = ConStatii();
   if (varstt.size() && constt.size()) {
-    auto mv = GetValuePresolver().PostsolveBasis(
+    auto mv = GetPresolver().PostsolveBasis(
       { std::move(varstt),
         {{{ CG_Linear, std::move(constt) }}} });
     varstt = mv.GetVarValues()();
@@ -644,7 +644,7 @@ SolutionBasis CoptBackend::GetBasis() {
 }
 
 void CoptBackend::SetBasis(SolutionBasis basis) {
-  auto mv = GetValuePresolver().PresolveBasis(
+  auto mv = GetPresolver().PresolveBasis(
     { basis.varstt, basis.constt });
   auto varstt = mv.GetVarValues()();
   auto constt = mv.GetConValues()(CG_Linear);
@@ -664,7 +664,7 @@ IIS CoptBackend::GetIIS() {
   auto variis = VarsIIS();
   auto coniis = ConsIIS();
   // TODO: This can be moved to a parent class?
-  auto mv = GetValuePresolver().PostsolveIIS(
+  auto mv = GetPresolver().PostsolveIIS(
     { variis, coniis });
   return { mv.GetVarValues()(), mv.GetConValues()() };
 }
diff --git a/solvers/copt/coptbackend.h b/solvers/copt/coptbackend.h
index f6749a545..1be53c6a5 100644
--- a/solvers/copt/coptbackend.h
+++ b/solvers/copt/coptbackend.h
@@ -19,14 +19,14 @@
 #include <string>
 
 #include "mp/backend-mip.h"
-#include "mp/valcvt-base.h"
+#include "mp/presolve-base.h"
 #include "coptcommon.h"
 
 namespace mp {
 
 class CoptBackend :
     public MIPBackend<CoptBackend>,
-    public BasicValuePresolverKeeper,
+    public BasicPresolverKeeper,
     public CoptCommon
 {
   using BaseBackend = MIPBackend<CoptBackend>;
diff --git a/solvers/copt/coptmodelapi.cc b/solvers/copt/coptmodelapi.cc
index e0ad6835c..853dd38ee 100644
--- a/solvers/copt/coptmodelapi.cc
+++ b/solvers/copt/coptmodelapi.cc
@@ -11,7 +11,7 @@ namespace mp {
 /// for recompilation speed
 std::unique_ptr<BasicModelManager>
 CreateCoptModelMgr(CoptCommon& cc, Env& e,
-                     pre::BasicValuePresolver*& pPre) {
+                     pre::BasicPresolver*& pPre) {
   return CreateModelMgrWithFlatConverter<
       CoptModelAPI, MIPFlatConverter >(cc, e, pPre);
 }
diff --git a/solvers/copt/coptmodelapi.h b/solvers/copt/coptmodelapi.h
index c99848066..8616f9859 100644
--- a/solvers/copt/coptmodelapi.h
+++ b/solvers/copt/coptmodelapi.h
@@ -6,7 +6,7 @@
 #include "mp/env.h"
 #include "coptcommon.h"
 #include "mp/flat/model_api_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/solvers/copt/main.cc b/solvers/copt/main.cc
index 00150c58d..99e820e24 100644
--- a/solvers/copt/main.cc
+++ b/solvers/copt/main.cc
@@ -8,6 +8,9 @@ extern "C" int main1(int, char **argv) {
       mp::RunBackendApp(argv, CreateCoptBackend);
 }
 
-extern "C" int main2(int, char** argv, CCallbacks cb) {
-  return mp::RunBackendApp(argv, CreateCoptBackend, cb);
-}
+extern "C" int main2(int, char** argv,
+  void* (*init)(), void (*check)(size_t, size_t, size_t),
+  const char* (*text)()) {
+  mp::BasicBackend::Callbacks callbacks = { init, check, text };
+  return mp::RunBackendApp(argv, CreateCoptBackend, callbacks);
+}
\ No newline at end of file
diff --git a/solvers/cplexdirect/cplexbackend.cc b/solvers/cplexdirect/cplexbackend.cc
index 4c8de092f..bf499a8d9 100644
--- a/solvers/cplexdirect/cplexbackend.cc
+++ b/solvers/cplexdirect/cplexbackend.cc
@@ -35,16 +35,16 @@ namespace mp {
 /// need it to convert solution data
 /// @return GurobiModelMgr
 std::unique_ptr<BasicModelManager>
-CreateCplexModelMgr(CplexCommon&, Env&, pre::BasicValuePresolver*&);
+CreateCplexModelMgr(CplexCommon&, Env&, pre::BasicPresolver*&);
 
 
 CplexBackend::CplexBackend() {
   OpenSolver();
 
-  pre::BasicValuePresolver* pPre;
+  pre::BasicPresolver* pPre;
   auto data = CreateCplexModelMgr(*this, *this, pPre);
   SetMM( std::move( data ) );
-  SetValuePresolver(pPre);
+  SetPresolver(pPre);
 
   /// Copy env/lp to ModelAPI
   copy_common_info_to_other();
@@ -58,7 +58,7 @@ void CplexBackend::OpenSolver() {
   int status;
   // Typically try the registered function first;
   // if not available call the solver's API function directly
-  const auto create_fn = GetCallbacks().init;
+  const auto& create_fn = GetCallbacks().cb_initsolver_;
   if (create_fn)
     set_env((CPXENVptr)create_fn());
   else
@@ -115,7 +115,7 @@ bool CplexBackend::IsQCP() const {
 
 
 Solution CplexBackend::GetSolution() {
-  auto mv = GetValuePresolver().PostsolveSolution(
+  auto mv = GetPresolver().PostsolveSolution(
         { PrimalSolution(), DualSolution() } );
   return { mv.GetVarValues()(), mv.GetConValues()(),
     GetObjectiveValues() };   // TODO postsolve obj values
diff --git a/solvers/cplexdirect/cplexbackend.h b/solvers/cplexdirect/cplexbackend.h
index 4f5a5e8a4..94c9870fc 100644
--- a/solvers/cplexdirect/cplexbackend.h
+++ b/solvers/cplexdirect/cplexbackend.h
@@ -19,14 +19,14 @@
 #include <string>
 
 #include "mp/backend-mip.h"
-#include "mp/valcvt-base.h"
+#include "mp/presolve-base.h"
 #include "cplexcommon.h"
 
 namespace mp {
 
 class CplexBackend :
     public MIPBackend<CplexBackend>,
-    public BasicValuePresolverKeeper,
+    public BasicPresolverKeeper,
     public CplexCommon
 {
   using BaseBackend = MIPBackend<CplexBackend>;
diff --git a/solvers/cplexdirect/cplexdirect-lib.c b/solvers/cplexdirect/cplexdirect-lib.c
index 260384d8d..688274a4a 100644
--- a/solvers/cplexdirect/cplexdirect-lib.c
+++ b/solvers/cplexdirect/cplexdirect-lib.c
@@ -10,16 +10,17 @@ APIEXPORT CPXLPptr AMPLloadmodel(int argc, char** argv, void** slvout) {
   const char* nl_filename = argv[1];
   const char *slv_opt= argv[2];
   AMPLS_MP_Solver* slv= AMPLSOpenCPLEX(slv_opt);
-  AMPLSLoadNLModel(slv, nl_filename);
+  int ret = -1;
+  ret = AMPLSLoadNLModel(slv, nl_filename);
   CPXLPptr mdl = GetCPLEXmodel(slv);
   *slvout = slv;
   return mdl;
 }
 
 APIEXPORT void AMPLwritesolution(AMPLS_MP_Solver* slv) {
-  AMPLSReportResults(slv);
+  AMPLSReportResults(&slv);
 }
 
 APIEXPORT void AMPLclosesolver(AMPLS_MP_Solver* slv) {
-  AMPLSCloseCPLEX(slv);
-}
+  AMPLSCloseCPLEX(&slv);
+}
\ No newline at end of file
diff --git a/solvers/cplexdirect/cplexmodelapi.cc b/solvers/cplexdirect/cplexmodelapi.cc
index d89e507aa..f4af65b2c 100644
--- a/solvers/cplexdirect/cplexmodelapi.cc
+++ b/solvers/cplexdirect/cplexmodelapi.cc
@@ -11,7 +11,7 @@ namespace mp {
 /// for recompilation speed
 std::unique_ptr<BasicModelManager>
 CreateCplexModelMgr(CplexCommon& cc, Env& e,
-                     pre::BasicValuePresolver*& pPre) {
+                     pre::BasicPresolver*& pPre) {
   return CreateModelMgrWithFlatConverter<
       CplexModelAPI, MIPFlatConverter >(cc, e, pPre);
 }
diff --git a/solvers/cplexdirect/cplexmodelapi.h b/solvers/cplexdirect/cplexmodelapi.h
index 0de9884f4..890600703 100644
--- a/solvers/cplexdirect/cplexmodelapi.h
+++ b/solvers/cplexdirect/cplexmodelapi.h
@@ -6,7 +6,7 @@
 #include "mp/env.h"
 #include "cplexcommon.h"
 #include "mp/flat/model_api_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/solvers/cplexdirect/main.cc b/solvers/cplexdirect/main.cc
index a7800d617..c7cced9ff 100644
--- a/solvers/cplexdirect/main.cc
+++ b/solvers/cplexdirect/main.cc
@@ -8,6 +8,9 @@ extern "C" int main1(int, char **argv) {
       mp::RunBackendApp(argv, CreateCplexBackend);
 }
 
-extern "C" int main2(int, char** argv, CCallbacks cb) {
-  return mp::RunBackendApp(argv, CreateCplexBackend, cb);
-}
+extern "C" int main2(int, char** argv,
+  void* (*init)(), void (*check)(size_t, size_t, size_t),
+  const char* (*text)()) {
+  mp::BasicBackend::Callbacks callbacks = { init, check, text };
+  return mp::RunBackendApp(argv, CreateCplexBackend, callbacks);
+}
\ No newline at end of file
diff --git a/solvers/gurobi/gurobi-lib.c b/solvers/gurobi/gurobi-lib.c
index 872a1744a..1ff5af312 100644
--- a/solvers/gurobi/gurobi-lib.c
+++ b/solvers/gurobi/gurobi-lib.c
@@ -14,7 +14,7 @@ APIEXPORT GRBmodel* AMPLdirectloadmodel(
   AMPLS_MP_Solver *slv = AMPLSOpenGurobi(slv_opt);
   if (!slv)
     return NULL;
-  AMPLSLoadNLModel(slv, nl_filename);
+  int ret = AMPLSLoadNLModel(slv, nl_filename);
   GRBmodel* mdl = GetGRBmodel(slv);
   *slvout = slv;
   return mdl;
diff --git a/solvers/gurobi/gurobibackend.cc b/solvers/gurobi/gurobibackend.cc
index 324c73465..59872b12b 100644
--- a/solvers/gurobi/gurobibackend.cc
+++ b/solvers/gurobi/gurobibackend.cc
@@ -33,14 +33,14 @@ namespace mp {
 /// @return GurobiModelMgr
 std::unique_ptr<BasicModelManager>
 CreateGurobiModelMgr(GurobiCommon& gc,
-                     Env& e, pre::BasicValuePresolver*& pPre);
+                     Env& e, pre::BasicPresolver*& pPre);
 
 
 GurobiBackend::GurobiBackend() {
-  pre::BasicValuePresolver* pPre;
+  pre::BasicPresolver* pPre;
   auto data = CreateGurobiModelMgr(*this, *this, pPre);
   SetMM( std::move( data ) );
-  SetValuePresolver(pPre);
+  SetPresolver(pPre);
 }
 
 GurobiBackend::~GurobiBackend() {
@@ -82,7 +82,7 @@ void GurobiBackend::OpenGurobi() {
   // Typically try the registered function first;
   // if not available call the solver's API function to create
   // an empty environment. Will be started later.
-  const auto create_fn = GetCallbacks().init;
+  const auto& create_fn = GetCallbacks().cb_initsolver_;
   if (create_fn)
     set_env((GRBenv*)create_fn());
   else 
@@ -113,12 +113,12 @@ void GurobiBackend::FinishOptionParsing() {
   else {
     // If a user defined function had been provided, the environment is assumed
     // as already started
-    if (!GetCallbacks().init)
+    if (!GetCallbacks().cb_initsolver_)
     {
       int res = GRBstartenv(env_ref());
       if (res)
       {
-        const auto diag = GetCallbacks().diagnostics;
+        const auto& diag = GetCallbacks().cb_diagnostics_;
         if (diag)
           diag();
         else {
@@ -218,7 +218,7 @@ std::vector<double> GurobiBackend::PrimalSolution() {
 }
 
 Solution GurobiBackend::GetSolution() {
-  auto mv = GetValuePresolver().PostsolveSolution(
+  auto mv = GetPresolver().PostsolveSolution(
         { PrimalSolution(), DualSolution() } );
   return { mv.GetVarValues()(), mv.GetConValues()(),
     GetObjectiveValues() };    // TODO postsolve obj values
@@ -277,7 +277,7 @@ double GurobiBackend::CurrentGrbPoolObjectiveValue() const {
 
 
 void GurobiBackend::MarkLazyOrUserCuts(ArrayRef<int> lazyVals) {
-  auto vm = GetValuePresolver().PresolveLazyUserCutFlags({
+  auto vm = GetPresolver().PresolveLazyUserCutFlags({
                                                       {}, lazyVals
                                                     });
   std::vector<int> lv_lin = vm.GetConValues()(CG_Linear);
@@ -305,7 +305,7 @@ SolutionBasis GurobiBackend::GetBasis() {
   std::vector<int> varstt = VarStatii();
   std::vector<int> constt = ConStatii();
   if (varstt.size() && constt.size()) {
-    auto mv = GetValuePresolver().PostsolveBasis(
+    auto mv = GetPresolver().PostsolveBasis(
           { std::move(varstt),
             {{{ CG_Linear, std::move(constt) }}} } );
     varstt = mv.GetVarValues()();
@@ -317,7 +317,7 @@ SolutionBasis GurobiBackend::GetBasis() {
 }
 
 void GurobiBackend::SetBasis(SolutionBasis basis) {
-  auto mv = GetValuePresolver().PresolveBasis(
+  auto mv = GetPresolver().PresolveBasis(
         { basis.varstt, basis.constt } );
   auto varstt = mv.GetVarValues()();
   auto constt = mv.GetConValues()(CG_Linear);
@@ -434,7 +434,7 @@ void GurobiBackend::ConStatii(ArrayRef<int> cst) {
 }
 
 void GurobiBackend::AddPrimalDualStart(Solution sol0) {
-  auto mv = GetValuePresolver().PresolveSolution(
+  auto mv = GetPresolver().PresolveSolution(
         { sol0.primal, sol0.dual } );
   auto x0 = mv.GetVarValues()();
   auto pi0 = mv.GetConValues()(CG_Linear);
@@ -501,7 +501,7 @@ ArrayRef<double> GurobiBackend::Ray() {
 
 ArrayRef<double> GurobiBackend::DRay() {
   auto fd = GrbGetDblAttrArray(GRB_DBL_ATTR_FARKASDUAL, NumLinCons());
-  auto vm = GetValuePresolver().PostsolveSolution({
+  auto vm = GetPresolver().PostsolveSolution({
                                                {},
                                                {{{CG_Linear, std::move(fd)}}}
                                              });
@@ -512,7 +512,7 @@ IIS GurobiBackend::GetIIS() {
   auto variis = VarsIIS();
   auto coniis = ConsIIS();
 
-  auto mv = GetValuePresolver().PostsolveIIS(
+  auto mv = GetPresolver().PostsolveIIS(
         { variis, coniis } );
   return { mv.GetVarValues()(), mv.GetConValues()() };
 }
@@ -816,7 +816,7 @@ void GurobiBackend::DoGurobiFeasRelax() {
     feasrelax().flag_orig_obj_available();
   }
   /// Gurobi 9.5 only relaxes linear constraints
-  auto mv = GetValuePresolver().PresolveSolution({
+  auto mv = GetPresolver().PresolveSolution({
                                               {},
                                               feasrelax().rhspen()
                                             });
diff --git a/solvers/gurobi/gurobibackend.h b/solvers/gurobi/gurobibackend.h
index ab4f3819a..6a7f510d5 100644
--- a/solvers/gurobi/gurobibackend.h
+++ b/solvers/gurobi/gurobibackend.h
@@ -20,13 +20,13 @@
 
 #include "gurobicommon.h"
 #include "mp/backend-mip.h"
-#include "mp/valcvt-base.h"
+#include "mp/presolve-base.h"
 
 namespace mp {
 
 class GurobiBackend :
     public MIPBackend<GurobiBackend>,
-    public BasicValuePresolverKeeper,
+    public BasicPresolverKeeper,
     public GurobiCommon
 {
   using BaseBackend = MIPBackend<GurobiBackend>;
diff --git a/solvers/gurobi/gurobimodelapi.cc b/solvers/gurobi/gurobimodelapi.cc
index b5cb1a5c4..77b0abfc1 100644
--- a/solvers/gurobi/gurobimodelapi.cc
+++ b/solvers/gurobi/gurobimodelapi.cc
@@ -8,7 +8,7 @@ namespace mp {
 /// for recompilation speed
 std::unique_ptr<BasicModelManager>
 CreateGurobiModelMgr(GurobiCommon& gc, Env& e,
-                     pre::BasicValuePresolver*& pPre) {
+                     pre::BasicPresolver*& pPre) {
   return CreateModelMgrWithFlatConverter<
       GurobiModelAPI, MIPFlatConverter >(gc, e, pPre);
 }
diff --git a/solvers/gurobi/gurobimodelapi.h b/solvers/gurobi/gurobimodelapi.h
index 9bfae4165..e247c5728 100644
--- a/solvers/gurobi/gurobimodelapi.h
+++ b/solvers/gurobi/gurobimodelapi.h
@@ -5,7 +5,7 @@
 
 #include "mp/env.h"
 #include "mp/flat/model_api_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 #include "gurobicommon.h"
 
diff --git a/solvers/gurobi/main.cc b/solvers/gurobi/main.cc
index 056324c3c..c3ca66d58 100644
--- a/solvers/gurobi/main.cc
+++ b/solvers/gurobi/main.cc
@@ -7,6 +7,9 @@ extern "C" int main1(int, char **argv) {
   return mp::RunBackendApp(argv, CreateGurobiBackend);
 }
 
-extern "C" int main2(int, char** argv, CCallbacks cb) {
-  return mp::RunBackendApp(argv, CreateGurobiBackend, cb);
+extern "C" int main2(int, char** argv,
+  void* (*init)(), void (*check)(size_t, size_t, size_t),
+  const char* (*text)(), void(*diag)()) {
+  mp::BasicBackend::Callbacks callbacks = { init, check, text, diag };
+  return mp::RunBackendApp(argv, CreateGurobiBackend, callbacks);
 }
diff --git a/solvers/highsdirect/highsdirectbackend.cc b/solvers/highsdirect/highsdirectbackend.cc
index 05c7d0492..a558b88a7 100644
--- a/solvers/highsdirect/highsdirectbackend.cc
+++ b/solvers/highsdirect/highsdirectbackend.cc
@@ -35,16 +35,16 @@ namespace mp {
 /// need it to convert solution data
 /// @return HighsModelMgr
 std::unique_ptr<BasicModelManager>
-CreateHighsModelMgr(HighsCommon&, Env&, pre::BasicValuePresolver*&);
+CreateHighsModelMgr(HighsCommon&, Env&, pre::BasicPresolver*&);
 
 
 HighsBackend::HighsBackend() {
   OpenSolver();
 
-  pre::BasicValuePresolver* pPre;
+  pre::BasicPresolver* pPre;
   auto data = CreateHighsModelMgr(*this, *this, pPre);
   SetMM( std::move( data ) );
-  SetValuePresolver(pPre);
+  SetPresolver(pPre);
 
   /// Copy env/lp to ModelAPI
   copy_common_info_to_other();
@@ -72,7 +72,7 @@ bool HighsBackend::IsQCP() const {
 }
 
 Solution HighsBackend::GetSolution() {
-  auto mv = GetValuePresolver().PostsolveSolution(
+  auto mv = GetPresolver().PostsolveSolution(
         { PrimalSolution(), DualSolution() } );
   return { mv.GetVarValues()(), mv.GetConValues()(),
     GetObjectiveValues() };   // TODO postsolve obj values
@@ -149,7 +149,7 @@ SolutionBasis HighsBackend::GetBasis() {
   std::vector<int> varstt = VarStatii();
   std::vector<int> constt = ConStatii();
   if (varstt.size() && constt.size()) {
-    auto mv = GetValuePresolver().PostsolveBasis(
+    auto mv = GetPresolver().PostsolveBasis(
       { std::move(varstt),
         {{{ CG_Linear, std::move(constt) }}} });
     varstt = mv.GetVarValues()();
@@ -161,7 +161,7 @@ SolutionBasis HighsBackend::GetBasis() {
 }
 
 void HighsBackend::SetBasis(SolutionBasis basis) {
-  auto mv = GetValuePresolver().PresolveBasis(
+  auto mv = GetPresolver().PresolveBasis(
     { basis.varstt, basis.constt });
   auto varstt = mv.GetVarValues()();
   auto constt = mv.GetConValues()(CG_Linear);
diff --git a/solvers/highsdirect/highsdirectbackend.h b/solvers/highsdirect/highsdirectbackend.h
index f881b4c87..299faa949 100644
--- a/solvers/highsdirect/highsdirectbackend.h
+++ b/solvers/highsdirect/highsdirectbackend.h
@@ -19,14 +19,14 @@
 #include <string>
 
 #include "mp/backend-mip.h"
-#include "mp/valcvt-base.h"
+#include "mp/presolve-base.h"
 #include "highsdirectcommon.h"
 
 namespace mp {
 
 class HighsBackend :
     public MIPBackend<HighsBackend>,
-    public BasicValuePresolverKeeper,
+    public BasicPresolverKeeper,
     public HighsCommon
 {
   using BaseBackend = MIPBackend<HighsBackend>;
diff --git a/solvers/highsdirect/highsdirectmodelapi.cc b/solvers/highsdirect/highsdirectmodelapi.cc
index 0586a92e6..92e62ba53 100644
--- a/solvers/highsdirect/highsdirectmodelapi.cc
+++ b/solvers/highsdirect/highsdirectmodelapi.cc
@@ -13,7 +13,7 @@ namespace mp {
 /// for recompilation speed
 std::unique_ptr<BasicModelManager>
 CreateHighsModelMgr(HighsCommon& cc, Env& e,
-                     pre::BasicValuePresolver*& pPre) {
+                     pre::BasicPresolver*& pPre) {
   return CreateModelMgrWithFlatConverter<
       HighsModelAPI, MIPFlatConverter >(cc, e, pPre);
 }
@@ -26,7 +26,7 @@ void HighsModelAPI::AddVariables(const VarArrayDef& v) {
   std::vector<double> costs(v.size(), 0);
   std::vector<double> lbs(v.size());
   std::vector<double> ubs(v.size());
-  for (int i = 0; i < v.size(); i++) {
+  for (size_t i = 0; i < v.size(); i++) {
     if (var::Type::INTEGER == v.ptype()[i]) intIndices.push_back(i);
     lbs[i] = std::isinf(v.plb()[i]) ? MinusInfinity() : v.plb()[i];
     ubs[i] = std::isinf(v.pub()[i]) ?  Infinity() : v.pub()[i];
@@ -64,7 +64,7 @@ void HighsModelAPI::SetQuadraticObjective(int iobj, const QuadraticObjective& qo
     int currentCol = 0, newCol = 0;
     startCols[0] = 0;
     // Convert to Highs Hessian upper triangular format
-    for (size_t i = 0; i < qt.size(); i++)
+    for (int i = 0; i < qt.size(); i++)
     {
       newCol = qt.vars1()[i];
       coeffs[i] = (qt.vars2()[i] == newCol) ? qt.coefs()[i]*2 : qt.coefs()[i];
diff --git a/solvers/highsdirect/highsdirectmodelapi.h b/solvers/highsdirect/highsdirectmodelapi.h
index b29f0c214..32e8aa674 100644
--- a/solvers/highsdirect/highsdirectmodelapi.h
+++ b/solvers/highsdirect/highsdirectmodelapi.h
@@ -6,7 +6,7 @@
 #include "mp/env.h"
 #include "highsdirectcommon.h"
 #include "mp/flat/model_api_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/solvers/ortoolsmp/CHANGES.ortoolsmp.md b/solvers/ortoolsmp/CHANGES.ortoolsmp.md
deleted file mode 100644
index 7e0a10590..000000000
--- a/solvers/ortoolsmp/CHANGES.ortoolsmp.md
+++ /dev/null
@@ -1,5 +0,0 @@
-Summary of recent updates to ORTOOLS for AMPL
-=============================================
-
-### 20220420
-- First release of mock driver
\ No newline at end of file
diff --git a/solvers/ortoolsmp/README.ortoolsmp.txt b/solvers/ortoolsmp/README.ortoolsmp.txt
deleted file mode 100644
index 137398179..000000000
--- a/solvers/ortoolsmp/README.ortoolsmp.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-ortools tutorial driver
-=======================
-
-The solver "ortools" is a mock solver, provided as an example - and as a template -
-on how to getting started using mp with FlatAPI to develop an mp-based solver interface.
\ No newline at end of file
diff --git a/solvers/ortoolsmp/main.cc b/solvers/ortoolsmp/main.cc
deleted file mode 100644
index 291daede8..000000000
--- a/solvers/ortoolsmp/main.cc
+++ /dev/null
@@ -1,10 +0,0 @@
-#include "mp/backend-app.h"
-#include "ortoolsmpbackend.h"
-
-/// Declare a backend factory
-std::unique_ptr<mp::BasicBackend> CreateOrtoolsBackend();
-
-int main(int, char** argv) {
-  return
-    mp::RunBackendApp(argv, CreateOrtoolsBackend);
-}
diff --git a/solvers/ortoolsmp/model-mgr-with-std-pb.cc b/solvers/ortoolsmp/model-mgr-with-std-pb.cc
deleted file mode 100644
index 2ffcce081..000000000
--- a/solvers/ortoolsmp/model-mgr-with-std-pb.cc
+++ /dev/null
@@ -1,8 +0,0 @@
-/**
- * Generate ModelManagerWithPB<mp::Problem>
- *
- * Having a separate .cc should improve compilation speed
- */
-
-#include "mp/model-mgr-with-std-pb.hpp"
-
diff --git a/solvers/ortoolsmp/ortoolsmp-ampls-c-api.h b/solvers/ortoolsmp/ortoolsmp-ampls-c-api.h
deleted file mode 100644
index 5b2379f3d..000000000
--- a/solvers/ortoolsmp/ortoolsmp-ampls-c-api.h
+++ /dev/null
@@ -1,29 +0,0 @@
-#ifndef ORTOOLSAMPLSCAPI_H
-#define ORTOOLSAMPLSCAPI_H
-/*
- * C API for MP/Ortools
- */
-
-#include "mp/ampls-c-api.h"
-
-/*
- * Below are Ortools-specific AMPLS API functions.
- * They complement the 'public' AMPLS API defined in ampls-c-api.h.
- */
-
-/// Initialize AMPLS ortools.
-/// @param slv: pointer to struct AMPLS_MP_Solver to be populated.
-/// @param slv_opt: a string of solver options
-/// (normally provided in the <solver>_options string).
-/// Can be NULL.
-/// @return 0 on success, otherwise see slv->warnings_and_or_errors_
-int AMPLSOpenOrtools(AMPLS_MP_Solver* slv, const char* slv_opt);
-
-/// Shut down solver instance
-void AMPLSCloseOrtools(AMPLS_MP_Solver* slv);
-
-/// Extract the Ortools model handle
-void* GetOrtoolsmodel(AMPLS_MP_Solver* slv);
-
-
-#endif // ORTOOLSAMPLSCAPI_H
diff --git a/solvers/ortoolsmp/ortoolsmp-lib.c b/solvers/ortoolsmp/ortoolsmp-lib.c
deleted file mode 100644
index 89fd58085..000000000
--- a/solvers/ortoolsmp/ortoolsmp-lib.c
+++ /dev/null
@@ -1,27 +0,0 @@
-#include "ortoolsmp-ampls-c-api.h"
-
-#ifdef _WIN32
-#define APIEXPORT __declspec(dllexport)
-#else
-#define APIEXPORT  __attribute__((visibility("default")))
-#endif
-
-APIEXPORT void* AMPLloadmodel(int argc, char** argv, void* slvout) {
-  const char* nl_filename = argv[1];
-  const char *slv_opt= argv[2];
-  AMPLS_MP_Solver slv;
-  int ret = -1;
-  ret = AMPLSOpenOrtools(&slv, slv_opt);
-  ret = AMPLSLoadNLModel(&slv, nl_filename);
-  void* mdl = GetOrtoolsmodel(&slv);
-  slvout = &slv;
-  return mdl;
-}
-
-APIEXPORT void AMPLwritesolution(AMPLS_MP_Solver* slv) {
-  AMPLSReportResults(&slv);
-}
-
-APIEXPORT void AMPLclosesolver(AMPLS_MP_Solver* slv) {
-  AMPLSCloseOrtools(&slv);
-}
\ No newline at end of file
diff --git a/solvers/ortoolsmp/ortoolsmpbackend.cc b/solvers/ortoolsmp/ortoolsmpbackend.cc
deleted file mode 100644
index 651ca132d..000000000
--- a/solvers/ortoolsmp/ortoolsmpbackend.cc
+++ /dev/null
@@ -1,299 +0,0 @@
-#include <vector>
-#include <climits>
-#include <cfloat>
-
-#include "mp/env.h"
-#include "mp/flat/model_api_base.h"
-#include "ortoolsmpbackend.h"
-
-extern "C" {
-  #include "ortoolsmp-ampls-c-api.h"    // Ortools AMPLS C API
-}
-#include "mp/ampls-cpp-api.h"
-
-namespace {
-
-
-bool InterruptOrtools(void* prob) {
-  //return ORTOOLS_Interrupt((ortools_prob*)prob);
-  return true;
-}
-
-}  // namespace {}
-
-std::unique_ptr<mp::BasicBackend> CreateOrtoolsBackend() {
-  return std::unique_ptr<mp::BasicBackend>{new mp::OrtoolsBackend()};
-}
-
-
-namespace mp {
-
-/// Create Ortools Model Manager
-/// @param gc: the Ortools common handle
-/// @param e: environment
-/// @param pre: presolver to be returned,
-/// need it to convert solution data
-/// @return OrtoolsModelMgr
-std::unique_ptr<BasicModelManager>
-CreateOrtoolsModelMgr(OrtoolsCommon&, Env&, pre::BasicValuePresolver*&);
-
-
-OrtoolsBackend::OrtoolsBackend() {
-  OpenSolver();
-
-  /// Create a ModelManager
-  pre::BasicValuePresolver* pPre;
-  auto data = CreateOrtoolsModelMgr(*this, *this, pPre);
-  SetMM( std::move( data ) );
-  SetValuePresolver(pPre);
-
-  /// Copy env/lp to ModelAPI
-  copy_common_info_to_other();
-}
-
-OrtoolsBackend::~OrtoolsBackend() {
-  CloseSolver();
-}
-
-void OrtoolsBackend::OpenSolver() {
-  int status = 0;
-  std::string solver = "SCIP";
-  auto lp = operations_research::MPSolver::CreateSolver(solver);
-  if (!lp)
-    throw std::runtime_error(fmt::format(
-      "Failed to create solver {}", solver));
-  set_lp(lp); // Assign it
-}
-
-void OrtoolsBackend::CloseSolver() {
-  delete lp();
-}
-
-const char* OrtoolsBackend::GetBackendName()
-  { return "OrtoolsBackend"; }
-
-std::string OrtoolsBackend::GetSolverVersion() {
-  return lp()->SolverVersion();
-}
-
-
-bool OrtoolsBackend::IsMIP() const {
-  return lp()->IsMIP();
-}
-
-bool OrtoolsBackend::IsQCP() const {
-  return false;
-}
-
-Solution OrtoolsBackend::GetSolution() {
-  auto mv = GetValuePresolver().PostsolveSolution(
-        { PrimalSolution(), DualSolution() } );
-  return { mv.GetVarValues()(), mv.GetConValues()(),
-    GetObjectiveValues() };   
-}
-
-ArrayRef<double> OrtoolsBackend::PrimalSolution() {
-  std::vector<double> x(NumVars());
-  for (std::size_t i = 0; i < NumVars(); i++)
-    x[i] = lp()->variable(i)->solution_value();
-  return x;
-}
-
-pre::ValueMapDbl OrtoolsBackend::DualSolution() {
-  return {{ { CG_Linear, DualSolution_LP() } }};
-}
-
-ArrayRef<double> OrtoolsBackend::DualSolution_LP() {
-  int num_cons = NumLinCons();
-  std::vector<double> pi(num_cons);
-  for (std::size_t i = 0; i < num_cons; i++)
-    pi[i] = lp()->constraint(i)->dual_value();
-  return pi;
-}
-
-double OrtoolsBackend::ObjectiveValue() const {
-  return lp()->Objective().Value();
-}
-
-double OrtoolsBackend::NodeCount() const {
-  return 0;
-}
-
-double OrtoolsBackend::SimplexIterations() const {
-  return 0;
-}
-
-int OrtoolsBackend::BarrierIterations() const {
-  return 0;
-}
-
-void OrtoolsBackend::ExportModel(const std::string &file) {
-  // TODO export proper by file extension
-  //ORTOOLS_CCALL(ORTOOLS_WriteLp(lp(), file.data()));
-}
-
-
-void OrtoolsBackend::SetInterrupter(mp::Interrupter *inter) {
-  inter->SetHandler(InterruptOrtools, lp());
-}
-
-void OrtoolsBackend::Solve() {
-  if (!storedOptions_.exportFile_.empty()) {
-    ExportModel(storedOptions_.exportFile_);
-  }
-  status_ = lp()->Solve();
-  WindupORTOOLSSolve();
-}
-
-void OrtoolsBackend::WindupORTOOLSSolve() { }
-
-void OrtoolsBackend::ReportResults() {
-  ReportORTOOLSResults();
-  BaseBackend::ReportResults();
-}
-
-void OrtoolsBackend::ReportORTOOLSResults() {
-  SetStatus( ConvertORTOOLSStatus() );
-  AddORTOOLSMessages();
-  if (need_multiple_solutions())
-    ReportORTOOLSPool();
-}
-std::vector<double> OrtoolsBackend::getPoolSolution(int i)
-{
-  std::vector<double> vars(NumVars());
- // ORTOOLS_CCALL(ORTOOLS_GetPoolSolution(lp(), i, NumVars(), NULL, vars.data()));
-  return vars;
-}
-double OrtoolsBackend::getPoolObjective(int i)
-{
-  double obj;
- // ORTOOLS_CCALL(ORTOOLS_GetPoolObjVal(lp(), i, &obj));
-  return obj;
-}
-void OrtoolsBackend::ReportORTOOLSPool() {
-  if (!IsMIP())
-    return;
-  int iPoolSolution = -1;
-  int nsolutions;
-  /*
-  while (++iPoolSolution < getIntAttr(ORTOOLS_INTATTR_POOLSOLS)) {
-    ReportIntermediateSolution(
-      { getPoolSolution(iPoolSolution),
-        {}, { getPoolObjective(iPoolSolution) } });
-  }
-  */
-}
-
-
-void OrtoolsBackend::AddORTOOLSMessages() {
-  if (auto ni = SimplexIterations())
-    AddToSolverMessage(
-          fmt::format("{} simplex iterations\n", ni));
-  if (auto nbi = BarrierIterations())
-    AddToSolverMessage(
-          fmt::format("{} barrier iterations\n", nbi));
-  if (auto nnd = NodeCount())
-    AddToSolverMessage(
-          fmt::format("{} branching nodes\n", nnd));
-}
-
-std::pair<int, std::string> OrtoolsBackend::ConvertORTOOLSStatus() {
-  namespace sol = mp::sol;
-  namespace ort = operations_research;
-  switch (status_)
-  {
-  case ort::MPSolver::OPTIMAL:
-    return { sol::SOLVED, "optimal solution" };
-  case ort::MPSolver::FEASIBLE:
-    return { sol::INTERRUPTED, "interrupted" };
-  case ort::MPSolver::INFEASIBLE:
-    return { sol::INFEASIBLE, "infeasible problem" };
-      /// proven unbounded.
-  case ort::MPSolver::UNBOUNDED:
-    return { sol::UNBOUNDED, "unbounded problem" };
-  case ort::MPSolver::ABNORMAL:
-  case ort::MPSolver::MODEL_INVALID:
-  case ort::MPSolver::NOT_SOLVED:
-    return { sol::FAILURE, "failed" };
-  default:
-    return { sol::UNKNOWN, "not solved" };
-  }
-}
-
-
-void OrtoolsBackend::FinishOptionParsing() {
-  int v=-1;
-  set_verbose_mode(v>0);
-}
-
-
-////////////////////////////// OPTIONS /////////////////////////////////
-
-
-static const mp::OptionValueInfo lp_values_method[] = {
-  { "-1", "Automatic (default)", -1},
-  { "1", "Dual simplex", 1},
-  { "2", "Barrier", 2},
-  { "3", "Crossover", 3},
-  { "4", "Concurrent (simplex and barrier simultaneously)", 4},
-};
-
-
-static const mp::OptionValueInfo alg_values_level[] = {
-  { "-1", "Automatic (default)", -1},
-  { "0", "Off", 0},
-  { "1", "Fast", 1},
-  { "2", "Normal", 2},
-  { "3", "Aggressive", 3}
-}; 
-
-static const mp::OptionValueInfo lp_dualprices_values_[] = {
-  { "-1", "Choose automatically (default)", -1},
-  { "0", "Use Devex pricing algorithm", 0},
-  { "1", "Using dual steepest-edge pricing algorithm", 1}
-};
-
-static const mp::OptionValueInfo lp_barorder_values_[] = {
-  { "-1", "Choose automatically (default)", -1},
-  { "0", "Approximate Minimum Degree (AMD)", 0},
-  { "1", "Nested Dissection (ND)", 1}
-};
-
-void OrtoolsBackend::InitCustomOptions() {
-
-  set_option_header(
-      "ORTOOLS Optimizer Options for AMPL\n"
-      "--------------------------------------------\n"
-      "\n"
-      "To set these options, assign a string specifying their values to the "
-      "AMPL option ``ortools_options``. For example::\n"
-      "\n"
-      "  ampl: option ortools_options 'mipgap=1e-6';\n");
-
-  AddStoredOption("tech:exportfile writeprob writemodel",
-      "Specifies the name of a file where to export the model before "
-      "solving it. This file name can have extension ``.lp()``, ``.mps``, etc. "
-      "Default = \"\" (don't export the model).",
-      storedOptions_.exportFile_);
-
-}
-
-} // namespace mp
-
-
-// AMPLs
-
-AMPLS_MP_Solver* AMPLSOpenOrtools(
-  const char* slv_opt) {
-  return AMPLS__internal__Open(std::unique_ptr<mp::BasicBackend>{new mp::OrtoolsBackend()},
-    slv_opt);
-}
-
-void AMPLSCloseOrtools(AMPLS_MP_Solver* slv) {
-  AMPLS__internal__Close(slv);
-}
-
-void* GetOrtoolsmodel(AMPLS_MP_Solver* slv) {
-  return
-    dynamic_cast<mp::OrtoolsBackend*>(AMPLSGetBackend(slv))->lp();
-}
diff --git a/solvers/ortoolsmp/ortoolsmpbackend.h b/solvers/ortoolsmp/ortoolsmpbackend.h
deleted file mode 100644
index a86ead954..000000000
--- a/solvers/ortoolsmp/ortoolsmpbackend.h
+++ /dev/null
@@ -1,131 +0,0 @@
-#ifndef MP_ORTOOLS_BACKEND_H_
-#define MP_ORTOOLS_BACKEND_H_
-
-#if __clang__
-# pragma clang diagnostic push
-# pragma clang diagnostic ignored "-Wunused-parameter"
-# pragma clang diagnostic ignored "-Wunused-private-field"
-#elif _MSC_VER
-# pragma warning(push)
-# pragma warning(disable: 4244)
-#endif
-
-#if __clang__
-# pragma clang diagnostic pop
-#elif _MSC_VER
-# pragma warning(pop)
-#endif
-
-#include <string>
-
-#include "mp/backend-mip.h"
-#include "mp/valcvt-base.h"
-#include "ortoolsmpcommon.h"
-
-namespace mp {
-
-class OrtoolsBackend :
-    public MIPBackend<OrtoolsBackend>,
-    public BasicValuePresolverKeeper,
-    public OrtoolsCommon
-{
-  using BaseBackend = MIPBackend<OrtoolsBackend>;
-
-
-  //////////////////// [[ The public interface ]] //////////////////////
-public:
-  OrtoolsBackend();
-  ~OrtoolsBackend();
-
-  /// Name displayed in messages
-  static const char* GetSolverName() { return "ortools"; }
-  std::string GetSolverVersion();
-  
-  static const char* GetAMPLSolverName() { return "ortools"; }
-  static const char* GetAMPLSolverLongName() { return "AMPL-ortools"; }
-  static const char* GetBackendName();
-  static const char* GetBackendLongName() { return nullptr; }
-
-  /// Chance for the Backend to init solver environment, etc
-  void InitOptionParsing() override { }
-  /// Chance to consider options immediately (open cloud, etc)
-  void FinishOptionParsing() override;
-
-
-
-  ////////////////////////////////////////////////////////////
-  /////////////// OPTIONAL STANDARD FEATURES /////////////////
-  ////////////////////////////////////////////////////////////
-  // Use this section to declare and implement some standard features
-  // that may or may not need additional functions. 
-  USING_STD_FEATURES;
-
-  /////////////////////////// Model attributes /////////////////////////
-  bool IsMIP() const override;
-  bool IsQCP() const override;
-  
-  //////////////////////////// SOLVING ///////////////////////////////
-
-  /// Note the interrupt notifier
-  void SetInterrupter(mp::Interrupter* inter) override;
-
-  /// Solve, no model modification any more.
-  /// Can report intermediate results via HandleFeasibleSolution() during this,
-  /// otherwise in ReportResults()
-  void Solve() override;
-
-  Solution GetSolution() override;
-  ArrayRef<double> GetObjectiveValues() override
-  { return std::vector<double>{ObjectiveValue()}; } 
-
-
-  //////////////////// [[ Implementation details ]] //////////////////////
-  ///////////////////////////////////////////////////////////////////////////////
-public:  // public for static polymorphism
-  void InitCustomOptions() override;
-
-protected:
-  void OpenSolver();
-  void CloseSolver();
-
-  void ExportModel(const std::string& file);
-
-  double ObjectiveValue() const;
-
-  /// Solution values. The vectors are emptied if not available
-  ArrayRef<double> PrimalSolution();
-  pre::ValueMapDbl DualSolution();
-  ArrayRef<double> DualSolution_LP();
-
-  void WindupORTOOLSSolve();
-
-  void ReportResults() override;
-  void ReportORTOOLSResults();
-  void ReportORTOOLSPool();
-
-  std::vector<double> getPoolSolution(int i);
-  double getPoolObjective(int i);
-
-  /// Solution attributes
-  double NodeCount() const;
-  double SimplexIterations() const;
-  int BarrierIterations() const;
-
-  std::pair<int, std::string> ConvertORTOOLSStatus();
-  void AddORTOOLSMessages();
-
-
-private:
-  /// These options are stored in the class
-  struct Options {
-    std::string exportFile_;
-  };
-  Options storedOptions_;
-
-  operations_research::MPSolver::ResultStatus status_;
-
-};
-
-}  // namespace mp
-
-#endif  // MP_ORTOOLS_BACKEND_H_
diff --git a/solvers/ortoolsmp/ortoolsmpcommon.cc b/solvers/ortoolsmp/ortoolsmpcommon.cc
deleted file mode 100644
index ef9862198..000000000
--- a/solvers/ortoolsmp/ortoolsmpcommon.cc
+++ /dev/null
@@ -1,70 +0,0 @@
-#include "mp/format.h"
-#include "ortoolsmpcommon.h"
-
-namespace mp {
-
-int OrtoolsCommon::getIntAttr(int name)  const {
-  int value = 0;
-  /* TODO Utility function to get the value of an integer attribute 
-  * from the solver API 
-  ORTOOLS_CCALL(ORTOOLS_GetIntAttr(lp_, name, &value)); */
-  return value;
-}
-double OrtoolsCommon::getDblAttr(const char* name) const  {
-  double value = 0;
-  /* TODO Utility function to get the value of an integer attribute
- * from the solver API
-  ORTOOLS_CCALL(ORTOOLS_GetDblAttr(lp_, name, &value)); */
-  return value;
-}
-
-int OrtoolsCommon::NumLinCons() const {
-  return lp()->NumConstraints();
-}
-
-int OrtoolsCommon::NumVars() const {
-  return lp()->NumVariables();
-}
-
-int OrtoolsCommon::NumObjs() const {
-  return 1;
-}
-
-int OrtoolsCommon::NumQPCons() const {
-  return 0;
-}
-
-int OrtoolsCommon::NumSOSCons() const {
-  return 0;
-}
-
-int OrtoolsCommon::NumIndicatorCons() const {
-  return 0;
-}
-
-void OrtoolsCommon::GetSolverOption(const char* key, int &value) const {
-  //ORTOOLS_CCALL( ORTOOLS_GetIntParam(lp_, key, &value) );
-}
-
-void OrtoolsCommon::SetSolverOption(const char* key, int value) {
-  //ORTOOLS_CCALL(ORTOOLS_SetIntParam(lp_, key, value));
-}
-
-void OrtoolsCommon::GetSolverOption(const char* key, double &value) const {
-  //ORTOOLS_CCALL(ORTOOLS_GetDblParam(lp_, key, &value) );
-}
-
-void OrtoolsCommon::SetSolverOption(const char* key, double value) {
- // ORTOOLS_CCALL(ORTOOLS_SetDblParam(lp_, key, value) );
-}
-
-void OrtoolsCommon::GetSolverOption(const char* key, std::string &value) const {
-  throw std::runtime_error("Not implemented"); // TODO
-}
-
-void OrtoolsCommon::SetSolverOption(const char* key, const std::string& value) {
-  throw std::runtime_error("Not implemented"); // TODO
-}
-
-
-} // namespace mp
diff --git a/solvers/ortoolsmp/ortoolsmpcommon.h b/solvers/ortoolsmp/ortoolsmpcommon.h
deleted file mode 100644
index 25d242f65..000000000
--- a/solvers/ortoolsmp/ortoolsmpcommon.h
+++ /dev/null
@@ -1,72 +0,0 @@
-#ifndef ORTOOLSCOMMON_H
-#define ORTOOLSCOMMON_H
-
-#include <string>
-#include <limits>
-
-#include "mp/backend-to-model-api.h"
-
-#include "ortools/linear_solver/linear_solver.h"
-
-
-/// The below would go into actual ...common.h:
-
-#include "mp/format.h"
-
-namespace mp {
-/// Information shared by both
-/// `OrtoolsBackend` and `OrtoolsModelAPI`
-struct OrtoolsCommonInfo {
-  operations_research::MPSolver* lp() const { return lp_; }
-  void set_lp(operations_research::MPSolver* lp) { lp_ = lp; }
-private:
-  operations_research::MPSolver*      lp_ = NULL;
-};
-
-
-/// Common API for Ortools classes
-class OrtoolsCommon :
-    public Backend2ModelAPIConnector<OrtoolsCommonInfo> {
-public:
-  /// These methods access Ortools options. Used by AddSolverOption()
-  void GetSolverOption(const char* key, int& value) const;
-  void SetSolverOption(const char* key, int value);
-  void GetSolverOption(const char* key, double& value) const;
-  void SetSolverOption(const char* key, double value);
-  void GetSolverOption(const char* key, std::string& value) const;
-  void SetSolverOption(const char* key, const std::string& value);
-
-  // TODO Typically solvers define their own infinity; use them here
-  static constexpr double Infinity() { return std::numeric_limits<double>::infinity();  }
-  static constexpr double MinusInfinity() { return -std::numeric_limits<double>::infinity(); }
-
-protected:
-  int getIntAttr(int name) const;
-  double getDblAttr(const char* name) const;
-
-  int NumLinCons() const;
-  int NumVars() const;
-  int NumObjs() const;
-  int NumQPCons() const;
-  int NumSOSCons() const;
-  int NumIndicatorCons() const;
-
-protected:
-  // TODO if desirable, provide function to create the solver's environment
-  //int (*createEnv) (solver_env**) = nullptr;
-  
-};
-
-
-/// Convenience macro
-// TODO This macro is useful to automatically throw an error if a function in the 
-// solver API does not return a valid errorcode. In this mock driver, we define it 
-// ourselves, normally this constant would be defined in the solver's API.
-#define ORTOOLS_RETCODE_OK 0
-#define ORTOOLS_CCALL( call ) do { if (int e = (call) != ORTOOLS_RETCODE_OK) \
-  throw std::runtime_error( \
-    fmt::format("  Call failed: '{}' with code {}", #call, e )); } while (0)
-
-} // namespace mp
-
-#endif // ORTOOLSCOMMON_H
diff --git a/solvers/ortoolsmp/ortoolsmpmodelapi.cc b/solvers/ortoolsmp/ortoolsmpmodelapi.cc
deleted file mode 100644
index d5ab23c2f..000000000
--- a/solvers/ortoolsmp/ortoolsmpmodelapi.cc
+++ /dev/null
@@ -1,77 +0,0 @@
-#include "ortoolsmpmodelapi.h"
-
-#include "mp/model-mgr-with-std-pb.h"
-#include "mp/flat/problem_flattener.h"
-#include "mp/flat/redef/MIP/converter_mip.h"
-#include "mp/flat/model_api_connect.h"
-
-namespace mp {
-
-/// Defining the function in ...modelapi.cc
-/// for recompilation speed
-std::unique_ptr<BasicModelManager>
-CreateOrtoolsModelMgr(OrtoolsCommon& cc, Env& e,
-                     pre::BasicValuePresolver*& pPre) {
-  return CreateModelMgrWithFlatConverter<
-      OrtoolsModelAPI, MIPFlatConverter >(cc, e, pPre);
-}
-
-
-void OrtoolsModelAPI::InitProblemModificationPhase() { }
-
-void OrtoolsModelAPI::AddVariables(const VarArrayDef& v) {
-  for (size_t i = 0; i < v.size(); ++i) {
-    lp()->MakeVar(v.plb()[i], v.pub()[i], 
-      v.ptype()[i] == var::Type::INTEGER, "");
-  }
-}
-
-void OrtoolsModelAPI::SetLinearObjective( int iobj, const LinearObjective& lo ) {
-  if (iobj<1) {
-    operations_research::MPObjective* const objective = lp()->MutableObjective();
-    for (int j = 0; j < lo.num_terms(); ++j) {
-      objective->SetCoefficient(lp()->variable(lo.vars()[j]), lo.coefs()[j]);
-    }
-    if (lo.obj_sense() == obj::Type::MAX)
-      objective->SetMaximization();
-    else
-      objective->SetMinimization();
-  } else {
-    throw std::runtime_error("Multiple objectives not supported");
-  }
-}
-
-
-void OrtoolsModelAPI::SetQuadraticObjective(int iobj, const QuadraticObjective& qo) {
-  throw std::runtime_error("Quadratic objective not supported");
-}
-
-void OrtoolsModelAPI::AddConstraint(const LinConRange& lc) {
-  auto c = lp()->MakeRowConstraint(lc.lb(), lc.ub());
-  for (size_t i = 0; i < lc.size(); i++)
-    c->SetCoefficient(lp()->variable(lc.var(i)), lc.coef(i));
-}
-
-void OrtoolsModelAPI::AddConstraint(const LinConLE& lc) {
-  auto c = lp()->MakeRowConstraint(lc.lb(), lc.ub());
-  for (size_t i = 0; i < lc.size(); i++)
-    c->SetCoefficient(lp()->variable(lc.var(i)), lc.coef(i));
-}
-void OrtoolsModelAPI::AddConstraint(const LinConEQ& lc) {
-  auto c = lp()->MakeRowConstraint(lc.lb(), lc.ub());
-  for (size_t i = 0; i < lc.size(); i++)
-    c->SetCoefficient(lp()->variable(lc.var(i)), lc.coef(i));
-}
-void OrtoolsModelAPI::AddConstraint(const LinConGE& lc) {
-  auto c = lp()->MakeRowConstraint(lc.lb(), lc.ub());
-  for (size_t i = 0; i < lc.size(); i++)
-    c->SetCoefficient(lp()->variable(lc.var(i)), lc.coef(i));
-}
-
-
-
-void OrtoolsModelAPI::FinishProblemModificationPhase() {
-}
-
-
-} // namespace mp
diff --git a/solvers/ortoolsmp/ortoolsmpmodelapi.h b/solvers/ortoolsmp/ortoolsmpmodelapi.h
deleted file mode 100644
index c53d59d81..000000000
--- a/solvers/ortoolsmp/ortoolsmpmodelapi.h
+++ /dev/null
@@ -1,71 +0,0 @@
-#ifndef ORTOOLSMODELAPI_H
-#define ORTOOLSMODELAPI_H
-
-#include <memory>
-
-#include "mp/env.h"
-#include "ortoolsmpcommon.h"
-#include "mp/flat/model_api_base.h"
-#include "mp/flat/constr_std.h"
-
-namespace mp {
-
-class OrtoolsModelAPI :
-    public OrtoolsCommon, public EnvKeeper,
-    public BasicFlatModelAPI
-{
-  using BaseModelAPI = BasicFlatModelAPI;
-
-public:
-  /// Construct
-  OrtoolsModelAPI(Env& e) : EnvKeeper(e) { }
-
-  /// Class name
-  static const char* GetTypeName() { return "OrtoolsModelAPI"; }
-
-  /// Called before problem input
-  void InitProblemModificationPhase();
-  /// After
-  void FinishProblemModificationPhase();
-
-  /// TODO Implement the following functions using the solver's API
-  void AddVariables(const VarArrayDef& );
-  void SetLinearObjective( int iobj, const LinearObjective& lo );
-  void SetQuadraticObjective(int iobj, const QuadraticObjective& qo);
-
-  //////////////////////////// GENERAL CONSTRAINTS ////////////////////////////
-  USE_BASE_CONSTRAINT_HANDLERS(BaseModelAPI)
-
-  /// TODO For each suppoted constraint type, add the ACCEPT_CONSTRAINT macro
-  /// and the relative AddConstraint function.
-  /// Below some typical constraint handlers of a MIP solver.
-  /// Further constraint types which could be handled natively by some solvers:
-  /// - IndicatorConstraint(Lin/Quad)(LE/EQ/GE)
-  /// - Multidirectional indicators Cond(Lin/Quad)Con(LT/LE/EQ/GE/GT), where
-  ///   the implication direction (</==/>) depends in the context
-  /// - Complementarity
-  /// - Logical, counting, piecewise-linear constraints.
-  /// See \a constraints_std.h and other drivers.
-
-
-  /// The linear range constraint, if fully supported with basis info etc.
-  ACCEPT_CONSTRAINT(LinConRange, Recommended, CG_Linear)
-  void AddConstraint(const LinConRange& lc);
-
-  /// LinCon(LE/EQ/GE) should have 'Recommended' for all backends
-  /// and have an implementation,
-  /// or a conversion rule is needed in a derived FlatConverter
-  ACCEPT_CONSTRAINT(LinConLE, Recommended, CG_Linear)
-  void AddConstraint(const LinConLE& lc);
-  ACCEPT_CONSTRAINT(LinConEQ, Recommended, CG_Linear)
-  void AddConstraint(const LinConEQ& lc);
-  ACCEPT_CONSTRAINT(LinConGE, Recommended, CG_Linear)
-  void AddConstraint(const LinConGE& lc);
-
-  
-
-};
-
-} // namespace mp
-
-#endif // ORTOOLSMODELAPI_H
diff --git a/solvers/visitor/visitorbackend.cc b/solvers/visitor/visitorbackend.cc
index 33ef1f9b0..dbbb194cb 100644
--- a/solvers/visitor/visitorbackend.cc
+++ b/solvers/visitor/visitorbackend.cc
@@ -35,17 +35,17 @@ namespace mp {
 /// need it to convert solution data
 /// @return VisitorModelMgr
 std::unique_ptr<BasicModelManager>
-CreateVisitorModelMgr(VisitorCommon&, Env&, pre::BasicValuePresolver*&);
+CreateVisitorModelMgr(VisitorCommon&, Env&, pre::BasicPresolver*&);
 
 
 VisitorBackend::VisitorBackend() {
   OpenSolver();
 
   /// Create a ModelManager
-  pre::BasicValuePresolver* pPre;
+  pre::BasicPresolver* pPre;
   auto data = CreateVisitorModelMgr(*this, *this, pPre);
   SetMM( std::move( data ) );
-  SetValuePresolver(pPre);
+  SetPresolver(pPre);
 
   /// Copy env/lp to ModelAPI
   copy_common_info_to_other();
@@ -129,7 +129,7 @@ bool VisitorBackend::IsQCP() const {
 }
 
 Solution VisitorBackend::GetSolution() {
-  auto mv = GetValuePresolver().PostsolveSolution(
+  auto mv = GetPresolver().PostsolveSolution(
         { PrimalSolution(), DualSolution() } );
   return { mv.GetVarValues()(), mv.GetConValues()(),
     GetObjectiveValues() };   // TODO postsolve obj values
@@ -511,7 +511,7 @@ SolutionBasis VisitorBackend::GetBasis() {
   std::vector<int> varstt = VarStatii();
   std::vector<int> constt = ConStatii();
   if (varstt.size() && constt.size()) {
-    auto mv = GetValuePresolver().PostsolveBasis(
+    auto mv = GetPresolver().PostsolveBasis(
       { std::move(varstt),
         {{{ CG_Linear, std::move(constt) }}} });
     varstt = mv.GetVarValues()();
@@ -523,7 +523,7 @@ SolutionBasis VisitorBackend::GetBasis() {
 }
 
 void VisitorBackend::SetBasis(SolutionBasis basis) {
-  auto mv = GetValuePresolver().PresolveBasis(
+  auto mv = GetPresolver().PresolveBasis(
     { basis.varstt, basis.constt });
   auto varstt = mv.GetVarValues()();
   auto constt = mv.GetConValues()(CG_Linear);
@@ -543,7 +543,7 @@ IIS VisitorBackend::GetIIS() {
   auto variis = VarsIIS();
   auto coniis = ConsIIS();
   // TODO: This can be moved to a parent class?
-  auto mv = GetValuePresolver().PostsolveIIS(
+  auto mv = GetPresolver().PostsolveIIS(
     { variis, coniis });
   return { mv.GetVarValues()(), mv.GetConValues()() };
 }
diff --git a/solvers/visitor/visitorbackend.h b/solvers/visitor/visitorbackend.h
index fec699b46..16c08ab74 100644
--- a/solvers/visitor/visitorbackend.h
+++ b/solvers/visitor/visitorbackend.h
@@ -19,14 +19,14 @@
 #include <string>
 
 #include "mp/backend-mip.h"
-#include "mp/valcvt-base.h"
+#include "mp/presolve-base.h"
 #include "visitorcommon.h"
 
 namespace mp {
 
 class VisitorBackend :
     public MIPBackend<VisitorBackend>,
-    public BasicValuePresolverKeeper,
+    public BasicPresolverKeeper,
     public VisitorCommon
 {
   using BaseBackend = MIPBackend<VisitorBackend>;
diff --git a/solvers/visitor/visitormodelapi.cc b/solvers/visitor/visitormodelapi.cc
index a0b78e9ba..d5a0791f8 100644
--- a/solvers/visitor/visitormodelapi.cc
+++ b/solvers/visitor/visitormodelapi.cc
@@ -11,7 +11,7 @@ namespace mp {
 /// for recompilation speed
 std::unique_ptr<BasicModelManager>
 CreateVisitorModelMgr(VisitorCommon& cc, Env& e,
-                     pre::BasicValuePresolver*& pPre) {
+                     pre::BasicPresolver*& pPre) {
   return CreateModelMgrWithFlatConverter<
       VisitorModelAPI, MIPFlatConverter >(cc, e, pPre);
 }
diff --git a/solvers/visitor/visitormodelapi.h b/solvers/visitor/visitormodelapi.h
index 3653a2507..a2f7f15e2 100644
--- a/solvers/visitor/visitormodelapi.h
+++ b/solvers/visitor/visitormodelapi.h
@@ -6,7 +6,7 @@
 #include "mp/env.h"
 #include "visitorcommon.h"
 #include "mp/flat/model_api_base.h"
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 namespace mp {
 
diff --git a/src/mp/flat/piecewise_linear.cpp b/src/mp/flat/piecewise_linear.cpp
index f4ddb11d1..7ba130b27 100644
--- a/src/mp/flat/piecewise_linear.cpp
+++ b/src/mp/flat/piecewise_linear.cpp
@@ -20,7 +20,7 @@
  Author: Gleb Belov
  */
 
-#include "mp/flat/constr_std.h"
+#include "mp/flat/constraints_std.h"
 
 mp::PLPoints::PLPoints(const PLSlopes &pls) {
   constexpr auto eps = 1.0;           // works?
diff --git a/src/solver.cc b/src/solver.cc
index 14fb42464..4c07ef15f 100644
--- a/src/solver.cc
+++ b/src/solver.cc
@@ -1028,7 +1028,7 @@ typedef struct AMPLS_MP__internal_T {
 AMPLS_MP_Solver* AMPLS__internal__Open(std::unique_ptr<mp::BasicBackend> p_be,
                           const char* slv_opt) {
   AMPLS_MP_Solver* slv = new AMPLS_MP_Solver();
-  AMPLS__internal__TryCatchWrapper( slv, [&]() {
+  int ret =  AMPLS__internal__TryCatchWrapper( slv, [&]() {
     auto ii = new AMPLS_MP__internal();
     slv->internal_info_ = ii;
     ii->p_be_ = std::move(p_be);
@@ -1050,7 +1050,10 @@ AMPLS_MP_Solver* AMPLS__internal__Open(std::unique_ptr<mp::BasicBackend> p_be,
   } );
   return slv;
 }
-
+/** Deallocate the mp-related info and the structure itself.
+* Before calling this function, a solver-specific implementation should
+* delete solver_info_ and user_info_ if allocated.
+*/
 void AMPLS__internal__Close(AMPLS_MP_Solver* slv) {
   assert(slv->internal_info_);
   delete (AMPLS_MP__internal*)slv->internal_info_;