From c40e360a51c8235ea19de466e12fb839edb26fff Mon Sep 17 00:00:00 2001
From: Ewout Kramer <ewout@fire.ly>
Date: Fri, 17 Jan 2025 17:12:12 +0100
Subject: [PATCH] Implemented IToSystemPrimitive on all applicable FHIR
 Primitives.

---
 src/Benchmarks/DateTimeBenchmark.cs           |   6 +-
 .../CompatibilitySuppressions.xml             | 560 ++++++++++++++++++
 src/Hl7.Fhir.Base/ElementModel/Types/Any.cs   |   2 +-
 .../ElementModel/Types/Boolean.cs             |   2 +-
 ...qlConvertible.cs => IToSystemPrimitive.cs} |  11 +-
 .../ElementModel/Types/Quantity.cs            |   2 +-
 .../FhirPath/Functions/ConversionOperators.cs |  59 +-
 src/Hl7.Fhir.Base/Model/Canonical.cs          | 216 +++----
 src/Hl7.Fhir.Base/Model/Code.cs               |  13 +-
 src/Hl7.Fhir.Base/Model/CodeOfT.cs            |   6 +-
 src/Hl7.Fhir.Base/Model/CodeableConcept.cs    |  16 +-
 src/Hl7.Fhir.Base/Model/CodeableReference.cs  |  42 +-
 src/Hl7.Fhir.Base/Model/Coding.cs             |  15 +-
 src/Hl7.Fhir.Base/Model/Date.cs               |  28 +-
 src/Hl7.Fhir.Base/Model/FhirBoolean.cs        |  27 +-
 src/Hl7.Fhir.Base/Model/FhirDateTime.cs       |  24 +-
 src/Hl7.Fhir.Base/Model/FhirDecimal.cs        |  27 +-
 src/Hl7.Fhir.Base/Model/FhirString.cs         |  11 +-
 src/Hl7.Fhir.Base/Model/FhirUri.cs            |  13 +-
 src/Hl7.Fhir.Base/Model/FhirUrl.cs            |  48 +-
 src/Hl7.Fhir.Base/Model/Instant.cs            |  65 +-
 src/Hl7.Fhir.Base/Model/Integer.cs            |  26 +-
 src/Hl7.Fhir.Base/Model/Integer64.cs          |  26 +-
 src/Hl7.Fhir.Base/Model/Markdown.cs           |  31 +-
 src/Hl7.Fhir.Base/Model/Oid.cs                |  38 +-
 src/Hl7.Fhir.Base/Model/PositiveInt.cs        |  26 +-
 src/Hl7.Fhir.Base/Model/Quantity.cs           |  29 +-
 src/Hl7.Fhir.Base/Model/Time.cs               |  23 +-
 src/Hl7.Fhir.Base/Model/UnsignedInt.cs        |  26 +-
 src/Hl7.Fhir.Base/Model/Uuid.cs               |  52 +-
 .../Model/DateTests.cs                        |   6 +-
 .../Model/DateTimeTests.cs                    |  10 +-
 .../Model/TimeTests.cs                        |   8 +-
 33 files changed, 1128 insertions(+), 366 deletions(-)
 rename src/Hl7.Fhir.Base/ElementModel/Types/{ICqlConvertible.cs => IToSystemPrimitive.cs} (68%)

diff --git a/src/Benchmarks/DateTimeBenchmark.cs b/src/Benchmarks/DateTimeBenchmark.cs
index 7eb86dff16..a1483ec136 100644
--- a/src/Benchmarks/DateTimeBenchmark.cs
+++ b/src/Benchmarks/DateTimeBenchmark.cs
@@ -10,10 +10,10 @@ public class DateTimeBenchmarks
         public void BenchmarkSetup()
         {
             _dateTimeInstance = new FhirDateTime(DATETIME);
-            _ = _dateTimeInstance.TryToDateTime(out var _); // trigger initial compile of regex
+            _ = _dateTimeInstance.TryToSystemDateTime(out var _); // trigger initial compile of regex
 
             _dateInstance = new Date(DATE);
-            _ = _dateInstance.TryToDate(out var _); // trigger initial compile of regex
+            _ = _dateInstance.TryToSystemDate(out var _); // trigger initial compile of regex
         }
 
         private const string DATETIME = "2023-07-11T13:00:00";
@@ -59,4 +59,4 @@ public DateTimeOffset DateToDTO_Cached()
             return result;
         }
     }
-}
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/CompatibilitySuppressions.xml b/src/Hl7.Fhir.Base/CompatibilitySuppressions.xml
index 362003322f..f6d525cfc1 100644
--- a/src/Hl7.Fhir.Base/CompatibilitySuppressions.xml
+++ b/src/Hl7.Fhir.Base/CompatibilitySuppressions.xml
@@ -15,6 +15,13 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.ICqlConvertible</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0001</DiagnosticId>
     <Target>T:Hl7.Fhir.ElementModel.Types.MetricConfiguration</Target>
@@ -43,6 +50,13 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Hl7.Fhir.Model.ElementValue</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0001</DiagnosticId>
     <Target>T:Hl7.Fhir.Model.IDeepComparable</Target>
@@ -134,6 +148,55 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Hl7.Fhir.Utility.Fail</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Hl7.Fhir.Utility.Fail`1</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Hl7.Fhir.Utility.IFailed</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Hl7.Fhir.Utility.Ok</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Hl7.Fhir.Utility.Ok`1</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Hl7.Fhir.Utility.Result</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0001</DiagnosticId>
+    <Target>T:Hl7.Fhir.Utility.Result`1</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>F:Hl7.Fhir.ElementModel.ScopedNode.Parent</Target>
@@ -141,6 +204,13 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>F:Hl7.Fhir.ElementModel.Types.Any.ArgNullException</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>F:Hl7.Fhir.Model.Resource.SyncLock</Target>
@@ -253,6 +323,188 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Any.CannotCastTo``1(Hl7.Fhir.ElementModel.Types.Any)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Any.NotSameTypeComparison(System.Object,System.Object)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Any.Parse(System.String,System.Type)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Any.propagateNull``1(System.Object,System.Func{``0})</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Any.TryParse(System.String,System.Type,System.Object@)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Code.op_Implicit(Hl7.Fhir.ElementModel.Types.Code)~Hl7.Fhir.ElementModel.Types.Concept</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Date.TryCompareTo(Hl7.Fhir.ElementModel.Types.Any)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Date.TryEquals(Hl7.Fhir.ElementModel.Types.Any)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.DateTime.TryCompareTo(Hl7.Fhir.ElementModel.Types.Any)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.DateTime.TryEquals(Hl7.Fhir.ElementModel.Types.Any)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Decimal.op_Explicit(Hl7.Fhir.ElementModel.Types.Decimal)~Hl7.Fhir.ElementModel.Types.String</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Integer.op_Implicit(Hl7.Fhir.ElementModel.Types.Integer)~Hl7.Fhir.ElementModel.Types.Decimal</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Integer.op_Implicit(Hl7.Fhir.ElementModel.Types.Integer)~Hl7.Fhir.ElementModel.Types.Long</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Integer.op_Implicit(Hl7.Fhir.ElementModel.Types.Integer)~Hl7.Fhir.ElementModel.Types.Quantity</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Long.op_Implicit(Hl7.Fhir.ElementModel.Types.Long)~Hl7.Fhir.ElementModel.Types.Decimal</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Long.op_Implicit(Hl7.Fhir.ElementModel.Types.Long)~Hl7.Fhir.ElementModel.Types.Quantity</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Quantity.op_Addition(Hl7.Fhir.ElementModel.Types.Quantity,Hl7.Fhir.ElementModel.Types.Quantity)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Quantity.op_Division(Hl7.Fhir.ElementModel.Types.Quantity,Hl7.Fhir.ElementModel.Types.Quantity)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Quantity.op_Multiply(Hl7.Fhir.ElementModel.Types.Quantity,Hl7.Fhir.ElementModel.Types.Quantity)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Quantity.op_Subtraction(Hl7.Fhir.ElementModel.Types.Quantity,Hl7.Fhir.ElementModel.Types.Quantity)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Quantity.TryCompareTo(Hl7.Fhir.ElementModel.Types.Any,Hl7.Fhir.ElementModel.Types.QuantityComparison)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Quantity.TryCompareTo(Hl7.Fhir.ElementModel.Types.Any)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Quantity.TryEquals(Hl7.Fhir.ElementModel.Types.Any,Hl7.Fhir.ElementModel.Types.QuantityComparison)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.String.#ctor</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Time.TryCompareTo(Hl7.Fhir.ElementModel.Types.Any)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Time.TryEquals(Hl7.Fhir.ElementModel.Types.Any)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:Hl7.Fhir.FhirPath.ElementNavFhirExtensions.HasValue(Hl7.Fhir.ElementModel.ITypedElement)</Target>
@@ -421,6 +673,55 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Date.op_Equality(Hl7.Fhir.Model.Date,Hl7.Fhir.Model.Date)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Date.op_GreaterThan(Hl7.Fhir.Model.Date,Hl7.Fhir.Model.Date)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Date.op_GreaterThanOrEqual(Hl7.Fhir.Model.Date,Hl7.Fhir.Model.Date)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Date.op_Inequality(Hl7.Fhir.Model.Date,Hl7.Fhir.Model.Date)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Date.op_LessThan(Hl7.Fhir.Model.Date,Hl7.Fhir.Model.Date)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Date.op_LessThanOrEqual(Hl7.Fhir.Model.Date,Hl7.Fhir.Model.Date)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Date.ToDate</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:Hl7.Fhir.Model.Date.ToDateTimeOffset</Target>
@@ -428,6 +729,111 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Date.TryToDate(Hl7.Fhir.ElementModel.Types.Date@)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.FhirDateTime.op_Equality(Hl7.Fhir.Model.FhirDateTime,Hl7.Fhir.Model.FhirDateTime)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.FhirDateTime.op_GreaterThan(Hl7.Fhir.Model.FhirDateTime,Hl7.Fhir.Model.FhirDateTime)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.FhirDateTime.op_GreaterThanOrEqual(Hl7.Fhir.Model.FhirDateTime,Hl7.Fhir.Model.FhirDateTime)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.FhirDateTime.op_Inequality(Hl7.Fhir.Model.FhirDateTime,Hl7.Fhir.Model.FhirDateTime)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.FhirDateTime.op_LessThan(Hl7.Fhir.Model.FhirDateTime,Hl7.Fhir.Model.FhirDateTime)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.FhirDateTime.op_LessThanOrEqual(Hl7.Fhir.Model.FhirDateTime,Hl7.Fhir.Model.FhirDateTime)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.FhirDateTime.ToDateTime</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.FhirDateTime.TryToDateTime(Hl7.Fhir.ElementModel.Types.DateTime@)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Instant.op_Equality(Hl7.Fhir.Model.Instant,Hl7.Fhir.Model.Instant)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Instant.op_GreaterThan(Hl7.Fhir.Model.Instant,Hl7.Fhir.Model.Instant)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Instant.op_GreaterThanOrEqual(Hl7.Fhir.Model.Instant,Hl7.Fhir.Model.Instant)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Instant.op_Inequality(Hl7.Fhir.Model.Instant,Hl7.Fhir.Model.Instant)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Instant.op_LessThan(Hl7.Fhir.Model.Instant,Hl7.Fhir.Model.Instant)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Instant.op_LessThanOrEqual(Hl7.Fhir.Model.Instant,Hl7.Fhir.Model.Instant)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:Hl7.Fhir.Model.Meta.get_ProfileElement</Target>
@@ -442,6 +848,13 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Quantity.ToQuantity</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:Hl7.Fhir.Model.Resource.get_HasVersionId</Target>
@@ -449,6 +862,62 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Time.op_Equality(Hl7.Fhir.Model.Time,Hl7.Fhir.Model.Time)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Time.op_GreaterThan(Hl7.Fhir.Model.Time,Hl7.Fhir.Model.Time)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Time.op_GreaterThanOrEqual(Hl7.Fhir.Model.Time,Hl7.Fhir.Model.Time)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Time.op_Inequality(Hl7.Fhir.Model.Time,Hl7.Fhir.Model.Time)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Time.op_LessThan(Hl7.Fhir.Model.Time,Hl7.Fhir.Model.Time)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Time.op_LessThanOrEqual(Hl7.Fhir.Model.Time,Hl7.Fhir.Model.Time)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Time.ToTime</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0002</DiagnosticId>
+    <Target>M:Hl7.Fhir.Model.Time.TryToTime(Hl7.Fhir.ElementModel.Types.Time@)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0002</DiagnosticId>
     <Target>M:Hl7.Fhir.Serialization.BaseFhirJsonPocoDeserializer.#ctor(Hl7.Fhir.Introspection.ModelInspector,Hl7.Fhir.Serialization.FhirJsonPocoDeserializerSettings)</Target>
@@ -1058,6 +1527,13 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0005</DiagnosticId>
+    <Target>M:Hl7.Fhir.ElementModel.Types.Any.TryConvertTo(System.Type,Hl7.Fhir.ElementModel.Types.Any@)</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0006</DiagnosticId>
     <Target>M:Hl7.Fhir.ElementModel.ITypedElement.Children(System.String)</Target>
@@ -1114,6 +1590,90 @@
     <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
     <IsBaselineSuppression>true</IsBaselineSuppression>
   </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Boolean</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Code</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Concept</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Date</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.DateTime</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Decimal</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Integer</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Long</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Quantity</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Ratio</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.String</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
+  <Suppression>
+    <DiagnosticId>CP0008</DiagnosticId>
+    <Target>T:Hl7.Fhir.ElementModel.Types.Time</Target>
+    <Left>lib/net8.0/Hl7.Fhir.Base.dll</Left>
+    <Right>lib/net8.0/Hl7.Fhir.Base.dll</Right>
+    <IsBaselineSuppression>true</IsBaselineSuppression>
+  </Suppression>
   <Suppression>
     <DiagnosticId>CP0008</DiagnosticId>
     <Target>T:Hl7.Fhir.Model.Attachment</Target>
diff --git a/src/Hl7.Fhir.Base/ElementModel/Types/Any.cs b/src/Hl7.Fhir.Base/ElementModel/Types/Any.cs
index 436df86b1f..596c3f6c59 100644
--- a/src/Hl7.Fhir.Base/ElementModel/Types/Any.cs
+++ b/src/Hl7.Fhir.Base/ElementModel/Types/Any.cs
@@ -17,7 +17,7 @@ namespace Hl7.Fhir.ElementModel.Types;
 /// <summary>
 /// The base class for all CQL/FhirPath types.
 /// </summary>
-public abstract class Any : ICqlConvertible
+public abstract class Any
 {
     /// <summary>
     /// Returns the concrete subclass of Any that is used to represent the
diff --git a/src/Hl7.Fhir.Base/ElementModel/Types/Boolean.cs b/src/Hl7.Fhir.Base/ElementModel/Types/Boolean.cs
index cf4d8fe828..126ceb34e6 100644
--- a/src/Hl7.Fhir.Base/ElementModel/Types/Boolean.cs
+++ b/src/Hl7.Fhir.Base/ElementModel/Types/Boolean.cs
@@ -13,7 +13,7 @@
 
 namespace Hl7.Fhir.ElementModel.Types;
 
-public class Boolean(bool value) : Any, ICqlEquatable, ICqlConvertible
+public class Boolean(bool value) : Any, ICqlEquatable
 {
     public static Boolean True = new(true);
     public static Boolean False = new(false);
diff --git a/src/Hl7.Fhir.Base/ElementModel/Types/ICqlConvertible.cs b/src/Hl7.Fhir.Base/ElementModel/Types/IToSystemPrimitive.cs
similarity index 68%
rename from src/Hl7.Fhir.Base/ElementModel/Types/ICqlConvertible.cs
rename to src/Hl7.Fhir.Base/ElementModel/Types/IToSystemPrimitive.cs
index c9aa581d8c..966b205b18 100644
--- a/src/Hl7.Fhir.Base/ElementModel/Types/ICqlConvertible.cs
+++ b/src/Hl7.Fhir.Base/ElementModel/Types/IToSystemPrimitive.cs
@@ -12,20 +12,23 @@
 
 namespace Hl7.Fhir.ElementModel.Types;
 
-public interface ICqlConvertible
+/// <summary>
+/// An interface to convert a model POCO into a CQL/FhirPath type.
+/// </summary>
+public interface IToSystemPrimitive
 {
     /// <summary>
     /// Tries to convert this object into a CQL/FhirPath type.
     /// </summary>
-    /// <param name="to">The subclass of Any to convert to.</param>
     /// <param name="result">If succesful, the converted object, otherwise null.</param>
-    bool TryConvertTo(Type to, [NotNullWhen(true)] out Any? result);
+    /// <returns>true if this model object has a CQL equivalent and the conversion succeeded, otherwise false.</returns>
+    bool TryConvertToSystemType([NotNullWhen(true)] out Any? result);
 }
 
 
 public static class CqlConvertible
 {
-    public static bool TryConvertTo<T>(this ICqlConvertible source, [NotNullWhen(true)] out T? result) where T : Any
+    public static bool TryConvertTo<T>(this Any source, [NotNullWhen(true)] out T? result) where T : Any
     {
         var success = source.TryConvertTo(typeof(T), out var any) && any is T;
 
diff --git a/src/Hl7.Fhir.Base/ElementModel/Types/Quantity.cs b/src/Hl7.Fhir.Base/ElementModel/Types/Quantity.cs
index 6c97ca4ba7..73ff2af33c 100644
--- a/src/Hl7.Fhir.Base/ElementModel/Types/Quantity.cs
+++ b/src/Hl7.Fhir.Base/ElementModel/Types/Quantity.cs
@@ -16,7 +16,7 @@
 namespace Hl7.Fhir.ElementModel.Types;
 
 public class Quantity(decimal value, string? unit, QuantityUnitSystem system)
-    : Any, IComparable, ICqlEquatable, ICqlOrderable, ICqlConvertible
+    : Any, IComparable, ICqlEquatable, ICqlOrderable
 {
     public const string UCUM = "http://unitsofmeasure.org";
     public const string UCUM_UNIT = "1";
diff --git a/src/Hl7.Fhir.Base/FhirPath/Functions/ConversionOperators.cs b/src/Hl7.Fhir.Base/FhirPath/Functions/ConversionOperators.cs
index ac73d5ba9c..9f8c81b7ec 100644
--- a/src/Hl7.Fhir.Base/FhirPath/Functions/ConversionOperators.cs
+++ b/src/Hl7.Fhir.Base/FhirPath/Functions/ConversionOperators.cs
@@ -22,11 +22,8 @@ internal static class ConversionOperators
         /// </summary>
         /// <param name="focus"></param>
         /// <returns></returns>
-        public static bool? ToBoolean(this Any focus)
-        {
-            if (focus is not ICqlConvertible c) return null;
-            return c.TryConvertTo<Boolean>(out var result) ? result.Value : null;
-        }
+        public static bool? ToBoolean(this Any focus) =>
+            focus.TryConvertTo<Boolean>(out var result) ? result.Value : null;
 
         /// <summary>
         /// FhirPath convertsToBoolean() function
@@ -41,11 +38,7 @@ internal static class ConversionOperators
         /// </summary>
         /// <param name="focus"></param>
         /// <returns></returns>
-        public static int? ToInteger(this Any focus)
-        {
-            if (focus is not ICqlConvertible c) return null;
-            return c.TryConvertTo<Integer>(out var result) ? result.Value : null;
-        }
+        public static int? ToInteger(this Any focus) => focus.TryConvertTo<Integer>(out var result) ? result.Value : null;
 
         /// <summary>
         /// FhirPath convertsToInteger() function.
@@ -60,11 +53,8 @@ internal static class ConversionOperators
         /// </summary>
         /// <param name="focus"></param>
         /// <returns></returns>
-        public static decimal? ToDecimal(this Any focus)
-        {
-            if (focus is not ICqlConvertible c) return null;
-            return c.TryConvertTo<Decimal>(out var result) ? result.Value : null;
-        }
+        public static decimal? ToDecimal(this Any focus) =>
+            focus.TryConvertTo<Decimal>(out var result) ? result.Value : null;
 
         /// <summary>
         /// FhirPath convertsToDecimal() function.
@@ -79,11 +69,7 @@ internal static class ConversionOperators
         /// </summary>
         /// <param name="focus"></param>
         /// <returns></returns>
-        public static long? ToLong(this Any focus)
-        {
-            if (focus is not ICqlConvertible c) return null;
-            return c.TryConvertTo<Long>(out var result) ? result.Value : null;
-        }
+        public static long? ToLong(this Any focus) => focus.TryConvertTo<Long>(out var result) ? result.Value : null;
 
 
         /// <summary>
@@ -99,11 +85,7 @@ internal static class ConversionOperators
         /// </summary>
         /// <param name="focus"></param>
         /// <returns></returns>
-        public static P.Quantity? ToQuantity(this Any focus)
-        {
-            if (focus is not ICqlConvertible c) return null;
-            return c.TryConvertTo<Quantity>(out var result) ? result : null;
-        }
+        public static P.Quantity? ToQuantity(this Any focus) => focus.TryConvertTo<Quantity>(out var result) ? result : null;
 
         /// <summary>
         /// FhirPath convertsToQuantity() function.
@@ -118,11 +100,8 @@ internal static class ConversionOperators
         /// </summary>
         /// <param name="focus"></param>
         /// <returns></returns>
-        public static string? ToStringRepresentation(this Any focus)
-        {
-            if (focus is not ICqlConvertible c) return null;
-            return c.TryConvertTo<String>(out var result) ? result.Value : null;
-        }
+        public static string? ToStringRepresentation(this Any focus) =>
+            focus.TryConvertTo<String>(out var result) ? result.Value : null;
 
         /// <summary>
         /// FhirPath convertsToString() function.
@@ -136,11 +115,7 @@ internal static class ConversionOperators
         /// </summary>
         /// <param name="focus"></param>
         /// <returns></returns>
-        public static P.Date? ToDate(this Any focus)
-        {
-            if (focus is not ICqlConvertible c) return null;
-            return c.TryConvertTo<Date>(out var result) ? result : null;
-        }
+        public static P.Date? ToDate(this Any focus) => focus.TryConvertTo<Date>(out var result) ? result : null;
 
 
         /// <summary>
@@ -156,11 +131,7 @@ internal static class ConversionOperators
         /// </summary>
         /// <param name="focus"></param>
         /// <returns></returns>
-        public static P.DateTime? ToDateTime(this Any focus)
-        {
-            if (focus is not ICqlConvertible c) return null;
-            return c.TryConvertTo<DateTime>(out var result) ? result : null;
-        }
+        public static P.DateTime? ToDateTime(this Any focus) => focus.TryConvertTo<DateTime>(out var result) ? result : null;
 
 
         /// <summary>
@@ -175,13 +146,7 @@ internal static class ConversionOperators
         /// </summary>
         /// <param name="focus"></param>
         /// <returns></returns>
-        public static P.Time? ToTime(this Any focus)
-        {
-            if (focus is not ICqlConvertible c) return null;
-            return c.TryConvertTo<Time>(out var result) ? result : null;
-
-        }
-
+        public static P.Time? ToTime(this Any focus) => focus.TryConvertTo<Time>(out var result) ? result : null;
 
         /// <summary>
         /// FhirPath convertsToTime() function.
diff --git a/src/Hl7.Fhir.Base/Model/Canonical.cs b/src/Hl7.Fhir.Base/Model/Canonical.cs
index c4bb95d8db..30b13bfc90 100644
--- a/src/Hl7.Fhir.Base/Model/Canonical.cs
+++ b/src/Hl7.Fhir.Base/Model/Canonical.cs
@@ -27,130 +27,136 @@ POSSIBILITY OF SUCH DAMAGE.
  
 */
 
+using P=Hl7.Fhir.ElementModel.Types;
 using Hl7.Fhir.Utility;
 using System;
+using System.Diagnostics.CodeAnalysis;
 
 #nullable enable
 
-namespace Hl7.Fhir.Model
+namespace Hl7.Fhir.Model;
+
+public partial class Canonical: P.IToSystemPrimitive
 {
-    public partial class Canonical
+    /// <summary>
+    /// Constructs a Canonical based on a given <see cref="Uri"/>.
+    /// </summary>
+    /// <param name="uri"></param>
+    public Canonical(Uri uri) : this(uri.OriginalString)
     {
-        /// <summary>
-        /// Constructs a Canonical based on a given <see cref="Uri"/>.
-        /// </summary>
-        /// <param name="uri"></param>
-        public Canonical(Uri uri) : this(uri?.OriginalString)
-        {
-            // nothing
-        }
+        // nothing
+    }
 
-        /// <summary>
-        /// Constructs a canonical from its components.
-        /// </summary>
-        public Canonical(string? uri, string? version, string? fragment)
-        {
-            if (uri == null) throw Error.ArgumentNull(nameof(uri));
-            if (uri.IndexOfAny(['|', '#']) != -1)
-                throw Error.Argument(nameof(uri), "cannot contain version/fragment data");
+    /// <summary>
+    /// Constructs a canonical from its components.
+    /// </summary>
+    public Canonical(string? uri, string? version, string? fragment)
+    {
+        if (uri == null) throw Error.ArgumentNull(nameof(uri));
+        if (uri.IndexOfAny(['|', '#']) != -1)
+            throw Error.Argument(nameof(uri), "cannot contain version/fragment data");
 
-            if (version != null && version.IndexOfAny(new[] { '|', '#' }) != -1)
-                throw Error.Argument(nameof(version), "cannot contain version/fragment data");
+        if (version != null && version.IndexOfAny(['|', '#']) != -1)
+            throw Error.Argument(nameof(version), "cannot contain version/fragment data");
 
-            if (fragment != null && fragment.IndexOfAny(new[] { '|', '#' }) != -1)
-                throw Error.Argument(nameof(fragment), "already contains version/fragment data");
+        if (fragment != null && fragment.IndexOfAny(['|', '#']) != -1)
+            throw Error.Argument(nameof(fragment), "already contains version/fragment data");
 
 
-            Value = uri +
+        Value = uri +
                 (version is not null ? "|" + version : null) +
                 (fragment is not null ? "#" + fragment : null);
-        }
+    }
 
-        /// <summary>
-        /// Deconstructs the canonical into its uri and version.
-        /// </summary>
-        public void Deconstruct(out string? uri, out string? version, out string? fragment)
-        {
-            uri = Uri;
-            version = Version;
-            fragment = Fragment;
-        }
+    /// <summary>
+    /// Deconstructs the canonical into its uri and version.
+    /// </summary>
+    public void Deconstruct(out string? uri, out string? version, out string? fragment)
+    {
+        uri = Uri;
+        version = Version;
+        fragment = Fragment;
+    }
 
-        /// <summary>
-        /// Converts a string to a canonical.
-        /// </summary>
-        /// <param name="value"></param>
-        public static implicit operator Canonical(string value) => new(value);
-
-        /// <summary>
-        /// Converts a canonical to a string.
-        /// </summary>
-        /// <param name="value"></param>
-        public static implicit operator string?(Canonical value) => value?.Value;
-
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => FhirUri.IsValidValue(value);
-
-        public static readonly Uri FHIR_CORE_PROFILE_BASE_URI = new(@"http://hl7.org/fhir/StructureDefinition/");
-        public static Canonical CanonicalUriForFhirCoreType(string typename) => new(FHIR_CORE_PROFILE_BASE_URI + typename);
-
-
-        /// <summary>
-        /// The version string of the canonical (if present).
-        /// </summary>
-        public string? Version => splitCanonical(Value).version;
-
-        /// <summary>
-        /// Optional anchor at the end of the canonical, without the '#' prefix.
-        /// </summary>
-        public string? Fragment => splitCanonical(Value).fragment;
-
-        /// <summary>
-        /// The uri part of the canonical, which is the canonical without the version indication.
-        /// </summary>
-        public string? Uri => splitCanonical(Value).url;
-
-        /// <summary>
-        /// Converts the canonical to a <see cref="System.Uri" />.
-        /// </summary>
-        /// <returns></returns>
-        public Uri ToUri() => new(Value, UriKind.RelativeOrAbsolute);
-
-        /// <summary>
-        /// Whether the canonical is a relative or an absolute uri.
-        /// </summary>
-        public bool IsAbsolute => ToUri().IsAbsoluteUri;
-
-        /// <summary>
-        /// Whether the canonical has a version part.
-        /// </summary>
-        public bool HasVersion => Version is not null;
-
-        /// <summary>
-        /// Whether the canonical end with an anchor.
-        /// </summary>
-        public bool HasAnchor => Fragment is not null;
-
-        private static (string? url, string? version, string? fragment) splitCanonical(string canonical)
-        {
-            var (rest, a) = splitOff(canonical, '#');
-            var (u, v) = splitOff(rest, '|');
+    /// <summary>
+    /// Converts a string to a canonical.
+    /// </summary>
+    /// <param name="value"></param>
+    public static implicit operator Canonical(string value) => new(value);
+
+    /// <summary>
+    /// Converts a canonical to a string.
+    /// </summary>
+    /// <param name="value"></param>
+    public static implicit operator string?(Canonical? value) => value?.Value;
+
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => FhirUri.IsValidValue(value);
+
+    public static readonly Uri FHIR_CORE_PROFILE_BASE_URI = new(@"http://hl7.org/fhir/StructureDefinition/");
+    public static Canonical CanonicalUriForFhirCoreType(string typename) => new(FHIR_CORE_PROFILE_BASE_URI + typename);
+
+
+    /// <summary>
+    /// The version string of the canonical (if present).
+    /// </summary>
+    public string? Version => splitCanonical(Value).version;
+
+    /// <summary>
+    /// Optional anchor at the end of the canonical, without the '#' prefix.
+    /// </summary>
+    public string? Fragment => splitCanonical(Value).fragment;
+
+    /// <summary>
+    /// The uri part of the canonical, which is the canonical without the version indication.
+    /// </summary>
+    public string? Uri => splitCanonical(Value).url;
+
+    /// <summary>
+    /// Converts the canonical to a <see cref="System.Uri" />.
+    /// </summary>
+    /// <returns></returns>
+    public Uri ToUri() => new(Value, UriKind.RelativeOrAbsolute);
+
+    /// <summary>
+    /// Whether the canonical is a relative or an absolute uri.
+    /// </summary>
+    public bool IsAbsolute => ToUri().IsAbsoluteUri;
+
+    /// <summary>
+    /// Whether the canonical has a version part.
+    /// </summary>
+    public bool HasVersion => Version is not null;
+
+    /// <summary>
+    /// Whether the canonical end with an anchor.
+    /// </summary>
+    public bool HasAnchor => Fragment is not null;
+
+    private static (string? url, string? version, string? fragment) splitCanonical(string canonical)
+    {
+        var (rest, a) = splitOff(canonical, '#');
+        var (u, v) = splitOff(rest, '|');
 
-            return (u == String.Empty ? null : u, v, a);
+        return (u == String.Empty ? null : u, v, a);
 
-            static (string, string?) splitOff(string url, char separator)
-            {
-                if (url.EndsWith(separator.ToString())) url = url.Substring(0, url.Length - 1);
-                var position = url.LastIndexOf(separator);
+        static (string, string?) splitOff(string url, char separator)
+        {
+            if (url.EndsWith(separator.ToString())) url = url[..^1];
+            var position = url.LastIndexOf(separator);
 
-                return position == -1 ?
-                    (url, null)
-                    : (url.Substring(0, position), url.Substring(position + 1));
-            }
+            return position == -1 ?
+                (url, null)
+                : (url[..position], url[(position + 1)..]);
         }
     }
-}
 
-#nullable restore
\ No newline at end of file
+    public P.String ToSystemString() => new(Value);
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemString();
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Code.cs b/src/Hl7.Fhir.Base/Model/Code.cs
index d6c3e2b0c0..b0f0587c3b 100644
--- a/src/Hl7.Fhir.Base/Model/Code.cs
+++ b/src/Hl7.Fhir.Base/Model/Code.cs
@@ -30,17 +30,26 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
+using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Text.RegularExpressions;
+using P=Hl7.Fhir.ElementModel.Types;
 
 namespace Hl7.Fhir.Model;
 
-public partial class Code : ICoded
+public partial class Code : ICoded, P.IToSystemPrimitive
 {
     /// <summary>
     /// Creates a <see cref="ElementModel.Types.Code"/> from an instance of a <see cref="Code"/>.
     /// </summary>
-    public virtual ElementModel.Types.Code ToSystemCode() => new(system: null, code: Value, display: null, version: null);
+    public virtual P.Code ToSystemCode() => new(system: null, code: Value, display: null, version: null);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemCode();
+        return true;
+    }
 
     /// <summary>
     /// Checks whether the given literal is correctly formatted.
diff --git a/src/Hl7.Fhir.Base/Model/CodeOfT.cs b/src/Hl7.Fhir.Base/Model/CodeOfT.cs
index 421efaf090..215e4809c8 100644
--- a/src/Hl7.Fhir.Base/Model/CodeOfT.cs
+++ b/src/Hl7.Fhir.Base/Model/CodeOfT.cs
@@ -39,7 +39,7 @@ POSSIBILITY OF SUCH DAMAGE.
 using System.Linq;
 using System.Runtime.Serialization;
 using COVE = Hl7.Fhir.Validation.CodedValidationException;
-using S = Hl7.Fhir.ElementModel.Types;
+using P = Hl7.Fhir.ElementModel.Types;
 
 namespace Hl7.Fhir.Model;
 
@@ -85,7 +85,7 @@ public Code(T? value)
 
     internal bool TryParseObjectValue(out T? value)
     {
-        value = default;
+        value = null;
 
         if (ObjectValue is string s && EnumUtility.ParseLiteral<T>(s) is { } parsed)
         {
@@ -97,7 +97,7 @@ internal bool TryParseObjectValue(out T? value)
 
     public override IEnumerable<Coding> ToCodings() => [new(Value?.GetSystem(), Value?.GetLiteral())];
 
-    public override S.Code ToSystemCode() =>
+    public override P.Code ToSystemCode() =>
         new(Value?.GetSystem(),
             Value?.GetLiteral() ?? throw new InvalidOperationException("Code must have a value in order to be useable to construct a System.Code."),
             display: null,
diff --git a/src/Hl7.Fhir.Base/Model/CodeableConcept.cs b/src/Hl7.Fhir.Base/Model/CodeableConcept.cs
index df253a1242..ba6296f01c 100644
--- a/src/Hl7.Fhir.Base/Model/CodeableConcept.cs
+++ b/src/Hl7.Fhir.Base/Model/CodeableConcept.cs
@@ -30,18 +30,26 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
+using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
-using S = Hl7.Fhir.ElementModel.Types;
+using P = Hl7.Fhir.ElementModel.Types;
 
 namespace Hl7.Fhir.Model;
 
-public partial class CodeableConcept : ICoded
+public partial class CodeableConcept : ICoded, P.IToSystemPrimitive
 {
-    public S.Concept ToSystemConcept()
+    public P.Concept ToSystemConcept()
     {
         var codes = Coding.Select(c => c.ToSystemCode());
-        return new S.Concept(codes, display: Text);
+        return new P.Concept(codes, display: Text);
+    }
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemConcept();
+        return true;
     }
 
     public IEnumerable<Coding> ToCodings() => Coding;
diff --git a/src/Hl7.Fhir.Base/Model/CodeableReference.cs b/src/Hl7.Fhir.Base/Model/CodeableReference.cs
index f217d8742f..a0deedcec8 100644
--- a/src/Hl7.Fhir.Base/Model/CodeableReference.cs
+++ b/src/Hl7.Fhir.Base/Model/CodeableReference.cs
@@ -8,11 +8,14 @@
 
 #nullable enable
 
+using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
 
 namespace Hl7.Fhir.Model;
 
-public partial class CodeableReference : ICoded
+public partial class CodeableReference : ICoded, P.IToSystemPrimitive
 {
     public CodeableReference()
     {
@@ -29,5 +32,42 @@ public CodeableReference(ResourceReference reference)
         Reference = reference;
     }
 
+    public P.Concept ToSystemConcept()
+    {
+        if(Concept is null) throw new InvalidOperationException("CodeableReference does not contain a CodeableConcept" +
+                                                                "and can therefore not be converted to a System Concept.");
+
+        return Concept.ToSystemConcept();
+    }
+
+    public P.String ToSystemString() =>
+        getReferenceString() ??
+        throw new InvalidOperationException("CodeableReference does not contain a Reference uri or identifier" +
+                                            " and can therefore not be converted to a System String.");
+
+    private P.String? getReferenceString() =>
+        (Reference.Reference ?? Reference.Identifier.Value) is { } reference
+            ? new P.String(reference)
+            : null;
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        if (Concept is not null)
+        {
+            result = ToSystemConcept();
+            return true;
+        }
+
+        if (getReferenceString() is {} reference)
+        {
+            result = reference;
+            return true;
+        }
+
+        result = null;
+        return false;
+    }
+
+
     public IEnumerable<Coding> ToCodings() => Concept?.ToCodings() ?? [];
 }
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Coding.cs b/src/Hl7.Fhir.Base/Model/Coding.cs
index 003651b3b7..14754cfa98 100644
--- a/src/Hl7.Fhir.Base/Model/Coding.cs
+++ b/src/Hl7.Fhir.Base/Model/Coding.cs
@@ -32,13 +32,14 @@ POSSIBILITY OF SUCH DAMAGE.
 
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Text;
-using S = Hl7.Fhir.ElementModel.Types;
+using P = Hl7.Fhir.ElementModel.Types;
 
 namespace Hl7.Fhir.Model;
 
 [DebuggerDisplay(@"\{{DebuggerDisplay,nq}}")]
-public partial class Coding: ICoded
+public partial class Coding: ICoded, P.IToSystemPrimitive
 {
     public Coding()
     {
@@ -75,6 +76,14 @@ public string DebuggerDisplay
         }
     }
 
-    public S.Code ToSystemCode() => new(System, Code, Display, Version);
+    public P.Code ToSystemCode() => new(System, Code, Display, Version);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemCode();
+        return true;
+    }
+
     public IEnumerable<Coding> ToCodings() => [this];
+
 }
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Date.cs b/src/Hl7.Fhir.Base/Model/Date.cs
index c0a6960da6..549c26d762 100644
--- a/src/Hl7.Fhir.Base/Model/Date.cs
+++ b/src/Hl7.Fhir.Base/Model/Date.cs
@@ -35,7 +35,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 namespace Hl7.Fhir.Model;
 
-public partial class Date
+public partial class Date: P.IToSystemPrimitive
 {
     public Date(int year, int month, int day)
         : this(string.Format(System.Globalization.CultureInfo.InvariantCulture, FhirDateTime.FMT_YEARMONTHDAY, year, month, day))
@@ -72,10 +72,10 @@ public Date(int year) : this(string.Format(System.Globalization.CultureInfo.Inva
     private static readonly P.Date INVALID_VALUE = P.Date.FromDateTimeOffset(DateTimeOffset.MinValue);
 
     /// <summary>
-    /// Converts a Fhir Date to a <see cref="P.Date"/>.
+    /// Converts a Fhir Date to a CQL <see cref="P.Date"/>.
     /// </summary>
     /// <returns>true if the Fhir Date contains a valid date string, false otherwise.</returns>
-    public bool TryToDate([NotNullWhen(true)] out P.Date? date)
+    public bool TryToSystemDate([NotNullWhen(true)] out P.Date? date)
     {
         if (_parsedValue is null)
         {
@@ -96,11 +96,25 @@ public bool TryToDate([NotNullWhen(true)] out P.Date? date)
     }
 
     /// <summary>
-    /// Converts a Fhir Date to a <see cref="P.Date"/>.
+    /// Converts a Fhir Date to a CQL <see cref="P.Date"/>.
     /// </summary>
     /// <returns>The Date, or null if the <see cref="Value"/> is null.</returns>
     /// <exception cref="FormatException">Thrown when the Value does not contain a valid FHIR Date.</exception>
-    public P.Date ToDate() => TryToDate(out var dt) ? dt : throw new FormatException($"String '{Value}' was not recognized as a valid date.");
+    public P.Date ToSystemDate() => TryToSystemDate(out var dt)
+        ? dt
+        : throw new FormatException($"String '{Value}' was not recognized as a valid date.");
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        if (TryToSystemDate(out var date))
+        {
+            result = date;
+            return true;
+        }
+
+        result = null;
+        return false;
+    }
 
     protected override void OnObjectValueChanged()
     {
@@ -117,7 +131,7 @@ public DateTimeOffset ToDateTimeOffset()
         if (Value == null) throw new InvalidOperationException("Date's value is null.");
 
         // TryToDate() will convert partial date/times by filling out to midnight/january 1 UTC
-        if (!TryToDate(out var dt))
+        if (!TryToSystemDate(out var dt))
             throw new FormatException($"Date '{Value}' was not recognized as a valid datetime.");
 
         // Since Value is not null and the parsed value is valid, dto will not be null
@@ -130,7 +144,7 @@ public DateTimeOffset ToDateTimeOffset()
     /// <returns>True if the value of the Fhir Date is not null and can be parsed as a DateTimeOffset, false otherwise.</returns>
     public bool TryToDateTimeOffset(out DateTimeOffset dto)
     {
-        if (Value is not null && TryToDate(out var dt))
+        if (Value is not null && TryToSystemDate(out var dt))
         {
             dto = dt.ToDateTimeOffset(TimeSpan.Zero);
             return true;
diff --git a/src/Hl7.Fhir.Base/Model/FhirBoolean.cs b/src/Hl7.Fhir.Base/Model/FhirBoolean.cs
index 7d702138b9..cd7e220faf 100644
--- a/src/Hl7.Fhir.Base/Model/FhirBoolean.cs
+++ b/src/Hl7.Fhir.Base/Model/FhirBoolean.cs
@@ -30,15 +30,24 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
-namespace Hl7.Fhir.Model
+using System.Diagnostics.CodeAnalysis;
+
+using P = Hl7.Fhir.ElementModel.Types;
+
+namespace Hl7.Fhir.Model;
+
+public partial class FhirBoolean: P.IToSystemPrimitive
 {
-    public partial class FhirBoolean
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => P.Boolean.TryParse(value, out _);
+
+    public P.Boolean ToSystemBoolean() => new(value: Value ?? false);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
     {
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => ElementModel.Types.Boolean.TryParse(value, out _);
+        result = ToSystemBoolean();
+        return true;
     }
-}
-
-#nullable restore
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/FhirDateTime.cs b/src/Hl7.Fhir.Base/Model/FhirDateTime.cs
index 0bf3974afb..6b35c9c0bd 100644
--- a/src/Hl7.Fhir.Base/Model/FhirDateTime.cs
+++ b/src/Hl7.Fhir.Base/Model/FhirDateTime.cs
@@ -37,7 +37,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 namespace Hl7.Fhir.Model;
 
-public partial class FhirDateTime
+public partial class FhirDateTime: P.IToSystemPrimitive
 {
     /// <summary>
     /// A <c>string.Format</c> pattern to use when formatting a full datetime with timezone.
@@ -98,7 +98,7 @@ public FhirDateTime(int year)
     /// Converts a FhirDateTime to a <see cref="P.DateTime"/>.
     /// </summary>
     /// <returns>true if the FhirDateTime contains a valid date/time string, false otherwise.</returns>
-    public bool TryToDateTime([NotNullWhen(true)] out P.DateTime? dateTime)
+    public bool TryToSystemDateTime([NotNullWhen(true)] out P.DateTime? dateTime)
     {
         if (_parsedValue is null)
         {
@@ -125,7 +125,7 @@ public bool TryToDateTime([NotNullWhen(true)] out P.DateTime? dateTime)
     /// </summary>
     /// <returns>The DateTime, or null if the <see cref="Value"/> is null.</returns>
     /// <exception cref="FormatException">Thrown when the Value does not contain a valid FHIR DateTime.</exception>
-    public P.DateTime ToDateTime() => TryToDateTime(out var dt) ? dt : throw new FormatException($"String '{Value}' was not recognized as a valid datetime.");
+    public P.DateTime ToSystemDateTime() => TryToSystemDateTime(out var dt) ? dt : throw new FormatException($"String '{Value}' was not recognized as a valid datetime.");
 
     protected override void OnObjectValueChanged()
     {
@@ -148,7 +148,7 @@ public DateTimeOffset ToDateTimeOffset(TimeSpan zone)
         if (Value == null) throw new InvalidOperationException("FhirDateTime's value is null.");
 
         // TryToDateTime() will convert partial date/times by filling out to midnight/january 1 UTC.
-        if (!TryToDateTime(out var dt))
+        if (!TryToSystemDateTime(out var dt))
             throw new FormatException($"DateTime '{Value}' was not recognized as a valid datetime.");
 
         // Since Value is not null and the parsed value is valid, dto will not be null
@@ -162,7 +162,7 @@ public DateTimeOffset ToDateTimeOffset(TimeSpan zone)
     /// specified timezone, false otherwise.</returns>
     public bool TryToDateTimeOffset(out DateTimeOffset dto)
     {
-        if (Value is not null && TryToDateTime(out var dt) && dt.Offset is not null)
+        if (Value is not null && TryToSystemDateTime(out var dt) && dt.Offset is not null)
         {
             dto = dt.ToDateTimeOffset(dt.Offset.Value);
             return true;
@@ -180,7 +180,7 @@ public bool TryToDateTimeOffset(out DateTimeOffset dto)
     /// <returns>True if the value of the FhirDateTime is not null and can be parsed as a DateTimeOffset, false otherwise.</returns>
     public bool TryToDateTimeOffset(TimeSpan defaultOffset, out DateTimeOffset dto)
     {
-        if (Value is not null && TryToDateTime(out var dt))
+        if (Value is not null && TryToSystemDateTime(out var dt))
         {
             dto = dt.ToDateTimeOffset(defaultOffset);
             return true;
@@ -190,6 +190,18 @@ public bool TryToDateTimeOffset(TimeSpan defaultOffset, out DateTimeOffset dto)
         return false;
     }
 
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        if (TryToSystemDateTime(out var dateTime))
+        {
+            result = dateTime;
+            return true;
+        }
+
+        result = null;
+        return false;
+    }
+
     /// <summary>
     /// Checks whether the given literal is correctly formatted.
     /// </summary>
diff --git a/src/Hl7.Fhir.Base/Model/FhirDecimal.cs b/src/Hl7.Fhir.Base/Model/FhirDecimal.cs
index 2613af9550..414c4b30b3 100644
--- a/src/Hl7.Fhir.Base/Model/FhirDecimal.cs
+++ b/src/Hl7.Fhir.Base/Model/FhirDecimal.cs
@@ -30,16 +30,23 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
-namespace Hl7.Fhir.Model
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
+
+namespace Hl7.Fhir.Model;
+
+public partial class FhirDecimal: P.IToSystemPrimitive
 {
-    public partial class FhirDecimal
-    {
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => ElementModel.Types.Decimal.TryParse(value, out _);
-    }
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => P.Decimal.TryParse(value, out _);
 
-}
+    public P.Decimal ToSystemDecimal() => new(value: Value ?? 0);
 
-#nullable restore
\ No newline at end of file
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemDecimal();
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/FhirString.cs b/src/Hl7.Fhir.Base/Model/FhirString.cs
index 283970c2cb..bb15ef5f38 100644
--- a/src/Hl7.Fhir.Base/Model/FhirString.cs
+++ b/src/Hl7.Fhir.Base/Model/FhirString.cs
@@ -30,10 +30,12 @@ POSSIBILITY OF SUCH DAMAGE.
 #nullable enable
 
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
 
 namespace Hl7.Fhir.Model;
 
-public partial class FhirString : ICoded
+public partial class FhirString : ICoded, P.IToSystemPrimitive
 {
     /// <summary>
     /// Checks whether the given literal is correctly formatted.
@@ -42,6 +44,13 @@ public partial class FhirString : ICoded
         
     // We do not match against the pattern since that is more expensive
 
+    public P.String ToSystemString() => new(Value);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemString();
+        return true;
+    }
 
     public IEnumerable<Coding> ToCodings() => [new(null, Value)];
 }
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/FhirUri.cs b/src/Hl7.Fhir.Base/Model/FhirUri.cs
index 8ac999ad8d..aa2a4cfe23 100644
--- a/src/Hl7.Fhir.Base/Model/FhirUri.cs
+++ b/src/Hl7.Fhir.Base/Model/FhirUri.cs
@@ -32,10 +32,12 @@ POSSIBILITY OF SUCH DAMAGE.
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
 
 namespace Hl7.Fhir.Model;
 
-public partial class FhirUri : ICoded
+public partial class FhirUri : ICoded, P.IToSystemPrimitive
 {
     public FhirUri(Uri uri)
     {
@@ -73,5 +75,14 @@ public static bool IsValidValue(string value)
         return true;
     }
 
+    public P.String ToSystemString() => new(Value);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemString();
+        return true;
+    }
+
+
     public IEnumerable<Coding> ToCodings() => [new(null, Value)];
 }
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/FhirUrl.cs b/src/Hl7.Fhir.Base/Model/FhirUrl.cs
index b152cf058e..7aba231eba 100644
--- a/src/Hl7.Fhir.Base/Model/FhirUrl.cs
+++ b/src/Hl7.Fhir.Base/Model/FhirUrl.cs
@@ -30,32 +30,40 @@ POSSIBILITY OF SUCH DAMAGE.
 #nullable enable
 
 using System;
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
 
-namespace Hl7.Fhir.Model
+namespace Hl7.Fhir.Model;
+
+public partial class FhirUrl: P.IToSystemPrimitive
 {
-    public partial class FhirUrl
+    public FhirUrl(Uri uri)
     {
-        public FhirUrl(Uri uri)
+        Value = uri.OriginalString;
+    }
+
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value)
+    {
+        try
         {
-            Value = uri.OriginalString;
+            var uri = new Uri(value, UriKind.RelativeOrAbsolute);
+            return true;
         }
-
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value)
+        catch
         {
-            try
-            {
-                var uri = new Uri(value, UriKind.RelativeOrAbsolute);
-                return true;
-            }
-            catch
-            {
-                return false;
-            }
+            return false;
         }
     }
-}
 
-#nullable restore
\ No newline at end of file
+    public P.String ToSystemString() => new(Value);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemString();
+        return true;
+    }
+
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Instant.cs b/src/Hl7.Fhir.Base/Model/Instant.cs
index d47646d92a..699033d75b 100644
--- a/src/Hl7.Fhir.Base/Model/Instant.cs
+++ b/src/Hl7.Fhir.Base/Model/Instant.cs
@@ -30,33 +30,52 @@ POSSIBILITY OF SUCH DAMAGE.
 #nullable enable
 
 using System;
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
 
-namespace Hl7.Fhir.Model
+namespace Hl7.Fhir.Model;
+
+public partial class Instant: P.IToSystemPrimitive
 {
-    public partial class Instant
+    public static Instant FromLocalDateTime(int year, int month, int day,
+        int hour, int min, int sec, int millis = 0) =>
+        new(new DateTimeOffset(year, month, day, hour, min, sec, millis, DateTimeOffset.Now.Offset));
+
+
+    public static Instant FromDateTimeUtc(int year, int month, int day,
+        int hour, int min, int sec, int millis = 0) =>
+        new(new DateTimeOffset(year, month, day, hour, min, sec, millis,
+            TimeSpan.Zero));
+
+    /// <summary>
+    /// Returns an Instant initialized with the current date and time.
+    /// </summary>
+    /// <returns></returns>
+    public static Instant Now() => new(DateTimeOffset.Now);
+
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => ElementModel.Types.DateTime.TryParse(value, out var dateTime) &&
+                                                     dateTime.Precision >= ElementModel.Types.DateTimePrecision.Second && dateTime.HasOffset;
+
+    public P.DateTime ToSystemDateTime() =>
+        Value is not null ? P.DateTime.FromDateTimeOffset(Value.Value) :
+           throw new InvalidOperationException("Instant's value is null and can therefore not be converted to a System DateTime.");
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
     {
-        public static Instant FromLocalDateTime(int year, int month, int day,
-                    int hour, int min, int sec, int millis = 0) =>
-            new(new DateTimeOffset(year, month, day, hour, min, sec, millis, DateTimeOffset.Now.Offset));
-
-
-        public static Instant FromDateTimeUtc(int year, int month, int day,
-                                            int hour, int min, int sec, int millis = 0) =>
-            new(new DateTimeOffset(year, month, day, hour, min, sec, millis,
-                                   TimeSpan.Zero));
-
-        /// <summary>
-        /// Returns an Instant initialized with the current date and time.
-        /// </summary>
-        /// <returns></returns>
-        public static Instant Now() => new(DateTimeOffset.Now);
-
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => ElementModel.Types.DateTime.TryParse(value, out var dateTime) &&
-            dateTime.Precision >= ElementModel.Types.DateTimePrecision.Second && dateTime.HasOffset;
+        if (Value is not null)
+        {
+            result = ToSystemDateTime();
+            return true;
+        }
+
+        result = null;
+        return false;
     }
+
+
 }
 
 #nullable restore
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Integer.cs b/src/Hl7.Fhir.Base/Model/Integer.cs
index 95d680a122..f7559f0bd3 100644
--- a/src/Hl7.Fhir.Base/Model/Integer.cs
+++ b/src/Hl7.Fhir.Base/Model/Integer.cs
@@ -30,15 +30,23 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
-namespace Hl7.Fhir.Model
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
+
+namespace Hl7.Fhir.Model;
+
+public partial class Integer: P.IToSystemPrimitive
 {
-    public partial class Integer
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => ElementModel.Types.Integer.TryParse(value, out _);
+
+    public P.Integer ToSystemInteger() => new(value: Value ?? 0);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
     {
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => ElementModel.Types.Integer.TryParse(value, out _);
+        result = ToSystemInteger();
+        return true;
     }
-}
-
-#nullable restore
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Integer64.cs b/src/Hl7.Fhir.Base/Model/Integer64.cs
index c4db1e51f8..6ea12bb588 100644
--- a/src/Hl7.Fhir.Base/Model/Integer64.cs
+++ b/src/Hl7.Fhir.Base/Model/Integer64.cs
@@ -30,15 +30,23 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
-namespace Hl7.Fhir.Model
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
+
+namespace Hl7.Fhir.Model;
+
+public partial class Integer64: P.IToSystemPrimitive
 {
-    public partial class Integer64
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => ElementModel.Types.Long.TryParse(value, out _);
+
+    public P.Long ToSystemLong() => new(value: Value ?? 0);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
     {
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => ElementModel.Types.Long.TryParse(value, out _);
+        result = ToSystemLong();
+        return true;
     }
-}
-
-#nullable restore
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Markdown.cs b/src/Hl7.Fhir.Base/Model/Markdown.cs
index b44b8de229..1875277658 100644
--- a/src/Hl7.Fhir.Base/Model/Markdown.cs
+++ b/src/Hl7.Fhir.Base/Model/Markdown.cs
@@ -30,21 +30,26 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
 
-namespace Hl7.Fhir.Model
-{
-    public partial class Markdown
-    {
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => FhirString.IsValidValue(value);
+namespace Hl7.Fhir.Model;
 
-        public static implicit operator string?(Markdown? md) => md?.Value;
-        public static implicit operator Markdown?(string? s) => s is not null ? new(s) : null;
+public partial class Markdown: P.IToSystemPrimitive
+{
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => FhirString.IsValidValue(value);
 
-    }
+    public static implicit operator string?(Markdown? md) => md?.Value;
+    public static implicit operator Markdown?(string? s) => s is not null ? new Markdown(s) : null;
 
-}
+    public P.String ToSystemString() => new(Value ?? string.Empty);
 
-#nullable restore
\ No newline at end of file
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemString();
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Oid.cs b/src/Hl7.Fhir.Base/Model/Oid.cs
index b74daf3d5c..107db73d9c 100644
--- a/src/Hl7.Fhir.Base/Model/Oid.cs
+++ b/src/Hl7.Fhir.Base/Model/Oid.cs
@@ -30,23 +30,29 @@ POSSIBILITY OF SUCH DAMAGE.
 #nullable enable
 
 using System.Text.RegularExpressions;
+using P = Hl7.Fhir.ElementModel.Types;
+using System.Diagnostics.CodeAnalysis;
 
-namespace Hl7.Fhir.Model
+namespace Hl7.Fhir.Model;
+
+public partial class Oid: P.IToSystemPrimitive
 {
-    public partial class Oid
-    {
-        /// <summary>
-        /// Creates a new <see cref="FhirUri"/> based on this oid.
-        /// </summary>
-        /// <returns></returns>
-        public FhirUri AsUri() => new(Value);
-
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => Regex.IsMatch(value, "^" + PATTERN + "$", RegexOptions.Singleline);
-    }
+    /// <summary>
+    /// Creates a new <see cref="FhirUri"/> based on this oid.
+    /// </summary>
+    /// <returns></returns>
+    public FhirUri AsUri() => new(Value);
 
-}
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => Regex.IsMatch(value, "^" + PATTERN + "$", RegexOptions.Singleline);
 
-#nullable restore
\ No newline at end of file
+    public P.String ToSystemString() => new(Value ?? string.Empty);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemString();
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/PositiveInt.cs b/src/Hl7.Fhir.Base/Model/PositiveInt.cs
index c92fc2f46e..862a7a63b5 100644
--- a/src/Hl7.Fhir.Base/Model/PositiveInt.cs
+++ b/src/Hl7.Fhir.Base/Model/PositiveInt.cs
@@ -30,15 +30,23 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
-namespace Hl7.Fhir.Model
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
+
+namespace Hl7.Fhir.Model;
+
+public partial class PositiveInt: P.IToSystemPrimitive
 {
-    public partial class PositiveInt
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => P.Integer.TryParse(value, out var parsed) && parsed.Value > 0;
+
+    public P.Long ToSystemLong() => new(value: Value ?? 0);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
     {
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => ElementModel.Types.Integer.TryParse(value, out var parsed) && parsed.Value > 0;
+        result = ToSystemLong();
+        return true;
     }
-}
-
-#nullable restore
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Quantity.cs b/src/Hl7.Fhir.Base/Model/Quantity.cs
index 234b90accd..ff0adc8bde 100644
--- a/src/Hl7.Fhir.Base/Model/Quantity.cs
+++ b/src/Hl7.Fhir.Base/Model/Quantity.cs
@@ -32,23 +32,34 @@ POSSIBILITY OF SUCH DAMAGE.
 
 using Hl7.Fhir.Utility;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using P = Hl7.Fhir.ElementModel.Types;
 
 namespace Hl7.Fhir.Model;
 
-public partial class Quantity : ICoded
+public partial class Quantity : ICoded, P.IToSystemPrimitive
 {
-    public P.Quantity? ToQuantity()
+    public P.Quantity ToSystemQuantity()
     {
-        if (Value != null)
-        {
-            if (Comparator != null)
-                throw Error.NotSupported("Cannot convert a Quantity with a comparator to a FhirPath Quantity");
+       if (Value == null)
+            throw Error.NotSupported("Cannot convert a Quantity without a value to a FhirPath Quantity.");
+
+       if(Comparator == null)
+           throw Error.NotSupported("Cannot convert a Quantity with a comparator to a FhirPath Quantity.");
+
+       return new P.Quantity(Value.Value, Code);
+    }
 
-            return new P.Quantity(Value.Value, Code);
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        if (Value is not null && Comparator is not null)
+        {
+            result = ToSystemQuantity();
+            return true;
         }
-        else
-            return null;
+
+        result = null;
+        return false;
     }
 
     public IEnumerable<Coding> ToCodings() => [new(System, Code)];
diff --git a/src/Hl7.Fhir.Base/Model/Time.cs b/src/Hl7.Fhir.Base/Model/Time.cs
index 4cb19e8ec3..23d1578ee4 100644
--- a/src/Hl7.Fhir.Base/Model/Time.cs
+++ b/src/Hl7.Fhir.Base/Model/Time.cs
@@ -37,7 +37,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 namespace Hl7.Fhir.Model;
 
-public partial class Time
+public partial class Time: P.IToSystemPrimitive
 {
     public const string FMT_HOURMINSEC = "{0:D2}:{1:D2}:{2:D2}";
 
@@ -68,7 +68,7 @@ public Time(int hour, int minute, int second) : this(string.Format(CultureInfo.I
     /// Converts a Fhir Time to a <see cref="P.Time"/>.
     /// </summary>
     /// <returns>true if the Fhir Time contains a valid time string, false otherwise.</returns>
-    public bool TryToTime([NotNullWhen(true)] out P.Time? time)
+    public bool TryToSystemTime([NotNullWhen(true)] out P.Time? time)
     {
         if (_parsedValue is null)
         {
@@ -95,7 +95,20 @@ public bool TryToTime([NotNullWhen(true)] out P.Time? time)
     /// </summary>
     /// <returns>The Time, or null if the <see cref="Value"/> is null.</returns>
     /// <exception cref="FormatException">Thrown when the Value does not contain a valid FHIR Time.</exception>
-    public P.Time ToTime() => TryToTime(out var dt) ? dt : throw new FormatException($"String '{Value}' was not recognized as a valid time.");
+    public P.Time ToSystemTime() => TryToSystemTime(out var dt) ? dt : throw new FormatException($"String '{Value}' was not recognized as a valid time.");
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        if (TryToSystemTime(out var dateTime))
+        {
+            result = dateTime;
+            return true;
+        }
+
+        result = null;
+        return false;
+    }
+
 
     protected override void OnObjectValueChanged()
     {
@@ -116,14 +129,14 @@ public TimeSpan ToTimeSpan() =>
     /// <returns>True if the value of the Fhir Time is not null and can be parsed as a Time without an offset, false otherwise.</returns>
     public bool TryToTimeSpan(out TimeSpan dto)
     {
-        if (Value is not null && TryToTime(out var dt) && !dt.HasOffset)
+        if (Value is not null && TryToSystemTime(out var dt) && !dt.HasOffset)
         {
             dto = dt.ToTimeSpan();
             return true;
         }
         else
         {
-            dto = default;
+            dto = TimeSpan.Zero;
             return false;
         }
     }
diff --git a/src/Hl7.Fhir.Base/Model/UnsignedInt.cs b/src/Hl7.Fhir.Base/Model/UnsignedInt.cs
index e3d6608c1c..4c701696ed 100644
--- a/src/Hl7.Fhir.Base/Model/UnsignedInt.cs
+++ b/src/Hl7.Fhir.Base/Model/UnsignedInt.cs
@@ -30,15 +30,23 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
-namespace Hl7.Fhir.Model
+using System.Diagnostics.CodeAnalysis;
+using P = Hl7.Fhir.ElementModel.Types;
+
+namespace Hl7.Fhir.Model;
+
+public partial class UnsignedInt: P.IToSystemPrimitive
 {
-    public partial class UnsignedInt
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => ElementModel.Types.Integer.TryParse(value, out var parsed) && parsed.Value >= 0;
+
+    public P.Long ToSystemLong() => new(value: Value ?? 0);
+
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
     {
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => ElementModel.Types.Integer.TryParse(value, out var parsed) && parsed.Value >= 0;
+        result = ToSystemLong();
+        return true;
     }
-}
-
-#nullable restore
\ No newline at end of file
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Base/Model/Uuid.cs b/src/Hl7.Fhir.Base/Model/Uuid.cs
index c059df0990..7569db8917 100644
--- a/src/Hl7.Fhir.Base/Model/Uuid.cs
+++ b/src/Hl7.Fhir.Base/Model/Uuid.cs
@@ -30,33 +30,39 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #nullable enable
 
+using System.Diagnostics.CodeAnalysis;
 using System.Text.RegularExpressions;
+using P = Hl7.Fhir.ElementModel.Types;
 
-namespace Hl7.Fhir.Model
+namespace Hl7.Fhir.Model;
+
+public partial class Uuid: P.IToSystemPrimitive
 {
-    public partial class Uuid
+    /// <summary>
+    /// Generates a new, random Uuid.
+    /// </summary>
+    /// <returns></returns>
+    public static Uuid Generate()
     {
-        /// <summary>
-        /// Generates a new, random Uuid.
-        /// </summary>
-        /// <returns></returns>
-        public static Uuid Generate()
-        {
-            var newUuid = "urn:uuid:" + System.Guid.NewGuid().ToString();
-            return new Uuid(newUuid);
-        }
-
-        /// <summary>
-        /// Creates a new <see cref="FhirUri"/> based on the value of this uuid.
-        /// </summary>
-        public FhirUri AsUri() => new(Value);
-
-        /// <summary>
-        /// Checks whether the given literal is correctly formatted.
-        /// </summary>
-        public static bool IsValidValue(string value) => Regex.IsMatch(value, "^" + PATTERN + "$", RegexOptions.Singleline);
+        var newUuid = "urn:uuid:" + System.Guid.NewGuid();
+        return new Uuid(newUuid);
     }
 
-}
+    /// <summary>
+    /// Creates a new <see cref="FhirUri"/> based on the value of this uuid.
+    /// </summary>
+    public FhirUri AsUri() => new(Value);
+
+    /// <summary>
+    /// Checks whether the given literal is correctly formatted.
+    /// </summary>
+    public static bool IsValidValue(string value) => Regex.IsMatch(value, "^" + PATTERN + "$", RegexOptions.Singleline);
+
+    public P.String ToSystemString() => new(Value ?? string.Empty);
 
-#nullable restore
\ No newline at end of file
+    bool P.IToSystemPrimitive.TryConvertToSystemType([NotNullWhen(true)] out P.Any? result)
+    {
+        result = ToSystemString();
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Support.Poco.Tests/Model/DateTests.cs b/src/Hl7.Fhir.Support.Poco.Tests/Model/DateTests.cs
index d8ff131380..dd08e48c37 100644
--- a/src/Hl7.Fhir.Support.Poco.Tests/Model/DateTests.cs
+++ b/src/Hl7.Fhir.Support.Poco.Tests/Model/DateTests.cs
@@ -99,17 +99,17 @@ public void ToDateTimeOffsetThrowsInvalidFormat()
         public void CanConvertToDateTime()
         {
             var dft = new Date(2023, 07, 11);
-            dft.TryToDate(out var dt).Should().BeTrue();
+            dft.TryToSystemDate(out var dt).Should().BeTrue();
             dt.Days.Should().Be(11);
             dt.Precision.Should().Be(ElementModel.Types.DateTimePrecision.Day);
 
             dft = new Date(2023, 7);
-            dft.TryToDate(out dt).Should().BeTrue();
+            dft.TryToSystemDate(out dt).Should().BeTrue();
             dt.Days.Should().BeNull();
             dt.Precision.Should().Be(ElementModel.Types.DateTimePrecision.Month);
 
             dft = new Date(null);
-            dft.TryToDate(out dt).Should().BeTrue();
+            dft.TryToSystemDate(out dt).Should().BeTrue();
             dt.Should().BeNull();
         }
     }
diff --git a/src/Hl7.Fhir.Support.Poco.Tests/Model/DateTimeTests.cs b/src/Hl7.Fhir.Support.Poco.Tests/Model/DateTimeTests.cs
index 9826d14a05..c9dcd6c843 100644
--- a/src/Hl7.Fhir.Support.Poco.Tests/Model/DateTimeTests.cs
+++ b/src/Hl7.Fhir.Support.Poco.Tests/Model/DateTimeTests.cs
@@ -151,23 +151,23 @@ public void TimeZoneHandlingNoTZ()
         public void CanConvertToDateTime()
         {
             var dft = new FhirDateTime(2023, 07, 11, 13, 0, 0, TimeSpan.FromHours(1));
-            dft.TryToDateTime(out var dt).Should().BeTrue();
+            dft.TryToSystemDateTime(out var dt).Should().BeTrue();
             dt.Hours.Should().Be(13);
             dt.Offset.Value.Hours.Should().Be(1);
             dt.Precision.Should().Be(ElementModel.Types.DateTimePrecision.Second);
 
             dft = new FhirDateTime(2023, 07, 11);
-            dft.TryToDateTime(out dt).Should().BeTrue();
+            dft.TryToSystemDateTime(out dt).Should().BeTrue();
             dt.Days.Should().Be(11);
             dt.HasOffset.Should().BeFalse();
             dt.Precision.Should().Be(ElementModel.Types.DateTimePrecision.Day);
 
             dft = new FhirDateTime("crap");
-            dft.TryToDateTime(out dt).Should().BeFalse();
+            dft.TryToSystemDateTime(out dt).Should().BeFalse();
 
             dft = new FhirDateTime(null);
-            dft.TryToDateTime(out dt).Should().BeTrue();
+            dft.TryToSystemDateTime(out dt).Should().BeTrue();
             dt.Should().BeNull();
         }
     }
-}
+}
\ No newline at end of file
diff --git a/src/Hl7.Fhir.Support.Poco.Tests/Model/TimeTests.cs b/src/Hl7.Fhir.Support.Poco.Tests/Model/TimeTests.cs
index 74a907862c..53fdce0d09 100644
--- a/src/Hl7.Fhir.Support.Poco.Tests/Model/TimeTests.cs
+++ b/src/Hl7.Fhir.Support.Poco.Tests/Model/TimeTests.cs
@@ -93,22 +93,22 @@ public void ToTimeSpanThrowsInvalidFormat()
         public void CanConvertToTime()
         {
             var dft = new Time(11, 12, 13);
-            dft.TryToTime(out var dt).Should().BeTrue();
+            dft.TryToSystemTime(out var dt).Should().BeTrue();
             dt.Minutes.Should().Be(12);
             dt.Precision.Should().Be(ElementModel.Types.DateTimePrecision.Second);
 
             dft = new Time("11:12");
-            dft.TryToTime(out dt).Should().BeTrue();
+            dft.TryToSystemTime(out dt).Should().BeTrue();
             dt.Seconds.Should().BeNull();
             dt.Precision.Should().Be(ElementModel.Types.DateTimePrecision.Minute);
 
             dft = new Time("11:12:34.123");
-            dft.TryToTime(out dt).Should().BeTrue();
+            dft.TryToSystemTime(out dt).Should().BeTrue();
             dt.Millis.Should().Be(123);
             dt.Precision.Should().Be(ElementModel.Types.DateTimePrecision.Fraction);
 
             dft = new Time(null);
-            dft.TryToTime(out dt).Should().BeTrue();
+            dft.TryToSystemTime(out dt).Should().BeTrue();
             dt.Should().BeNull();
         }
     }