diff --git a/src/Hl7.Fhir.STU3/Specification/Source/SnapshotSource.cs b/src/Hl7.Fhir.STU3/Specification/Source/SnapshotSource.cs
deleted file mode 100644
index 8700f8db37..0000000000
--- a/src/Hl7.Fhir.STU3/Specification/Source/SnapshotSource.cs
+++ /dev/null
@@ -1,106 +0,0 @@
-using Hl7.Fhir.Model;
-using Hl7.Fhir.Specification.Snapshot;
-using Hl7.Fhir.Utility;
-using System;
-using System.Diagnostics;
-using T=System.Threading.Tasks;
-
-namespace Hl7.Fhir.Specification.Source
-{
-    // Design:
-    // - SnapshotSource depends on SnapshotGenerator; NOT the other way around (!)
-    // - Ownership/composition: SnapshotSource => SnapshotGenerator => InternalSource
-    // - SnapshotGenerator rejects SnapshotSource as input argument (throw), to prevent recursion
-    // - SnapshotGenerator still supports stand-alone usage (w/o SnapshotSource), i.e. backwards-compatible
-    // - SnapshotGenerator class remains responsible for:
-    //   - detecting and handling recursion
-    //   - caching expanded root elements
-    //   - annotating snapshots
-
-    /// <summary>
-    /// Resolves resources from an internal <see cref="IResourceResolver"/> instance.
-    /// Ensures that resolved <see cref="StructureDefinition"/> resources have a snapshot component (re-generate on demand).
-    /// </summary>
-    [DebuggerDisplay(@"\{{DebuggerDisplay,nq}}")]
-    public class SnapshotSource : IResourceResolver, IAsyncResourceResolver
-    {
-        /// <summary>Creates a new instance of the <see cref="SnapshotSource"/> for the specified snapshot generator instance.</summary>
-        /// <param name="generator">A <see cref="SnapshotGenerator"/> instance.</param>
-        public SnapshotSource(SnapshotGenerator generator)
-        {
-            Generator = generator ?? throw Error.ArgumentNull(nameof(generator));
-        }
-
-        /// <summary>Creates a new instance of the <see cref="SnapshotSource"/> for the specified internal resolver.</summary>
-        /// <param name="source">An internal <see cref="IResourceResolver"/> instance. The implementation should be idempotent (i.e. cached), so the generated snapshots are persisted in memory.</param>
-        /// <param name="settings">Configuration settings for the snapshot generator.</param>
-        public SnapshotSource(IResourceResolver source, SnapshotGeneratorSettings settings)
-        {
-            // SnapshotGenerator ctor will throw if source or settings are null
-            Generator = new SnapshotGenerator(source, settings);
-        }
-
-        /// <summary>Creates a new instance of the <see cref="SnapshotSource"/> for the specified internal resolver.</summary>
-        /// <param name="source">An internal <see cref="IResourceResolver"/> instance. The implementation should be idempotent (i.e. cached), so the generated snapshots are persisted in memory.</param>
-        /// <param name="regenerate">Determines if the source should always discard any existing snapshot components provided by the internal source and force re-generation.</param>
-        public SnapshotSource(IResourceResolver source, bool regenerate)
-            : this(source, createSettings(regenerate)) { }
-
-        // Create default SnapshotGeneratorSettings, apply the specified regenerate flag
-        static SnapshotGeneratorSettings createSettings(bool regenerate)
-        {
-            var settings = SnapshotGeneratorSettings.CreateDefault();
-            settings.ForceRegenerateSnapshots = regenerate;
-            return settings;
-        }
-
-        /// <summary>Creates a new instance of the <see cref="SnapshotSource"/> for the specified internal resolver.</summary>
-        /// <param name="source">An internal <see cref="IResourceResolver"/> instance. The implementation should be idempotent (i.e. cached), so the generated snapshots are persisted in memory.</param>
-        public SnapshotSource(IResourceResolver source) 
-            : this(source, SnapshotGeneratorSettings.CreateDefault()) { }
-
-        /// <summary>Returns the internal <see cref="SnapshotGenerator"/> instance used by the source.</summary>
-        public SnapshotGenerator Generator { get; }
-
-        #region IResourceResolver
-
-        private IAsyncResourceResolver _resolver => Generator.AsyncResolver;
-
-        /// <summary>Find a resource based on its relative or absolute uri.</summary>
-        /// <remarks>The source ensures that resolved <see cref="StructureDefinition"/> instances have a snapshot component.</remarks>
-        public async T.Task<Resource> ResolveByUriAsync(string uri) => await ensureSnapshot(await _resolver.ResolveByUriAsync(uri).ConfigureAwait(false)).ConfigureAwait(false);
-
-        /// <inheritdoc cref="ResolveByUriAsync(string)"/>
-        [Obsolete("SnapshotSource now works best with asynchronous resolvers. Use ResolveByUriAsync() instead.")]
-        public Resource ResolveByUri(string uri) => TaskHelper.Await(() => ResolveByUriAsync(uri));
-
-        /// <summary>Find a (conformance) resource based on its canonical uri.</summary>
-        /// <remarks>The source ensures that resolved <see cref="StructureDefinition"/> instances have a snapshot component.</remarks>
-        public async T.Task<Resource> ResolveByCanonicalUriAsync(string uri) => await ensureSnapshot(await _resolver.ResolveByCanonicalUriAsync(uri).ConfigureAwait(false)).ConfigureAwait(false);
-
-        /// <inheritdoc cref="ResolveByCanonicalUriAsync(string)"/>
-        [Obsolete("SnapshotSource now works best with asynchronous resolvers. Use ResolveByCanonicalUriAsync() instead.")]
-        public Resource ResolveByCanonicalUri(string uri) => TaskHelper.Await(() => ResolveByCanonicalUriAsync(uri));
-
-        #endregion
-
-        // If the specified resource is a StructureDefinition,
-        // then ensure snapshot component is available, (re-)generate on demand
-        private async T.Task<Resource> ensureSnapshot(Resource res)
-        {
-            if (res is StructureDefinition sd)
-            {
-                if (!sd.HasSnapshot || Generator.Settings.ForceRegenerateSnapshots || !sd.Snapshot.IsCreatedBySnapshotGenerator())
-                {
-                    await Generator.UpdateAsync(sd).ConfigureAwait(false);
-                }
-            }
-            return res;
-        }
-
-        // Allow derived classes to override
-        // http://blogs.msdn.com/b/jaredpar/archive/2011/03/18/debuggerdisplay-attribute-best-practices.aspx
-        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
-        internal protected virtual string DebuggerDisplay => $"{GetType().Name} for {_resolver.DebuggerDisplayString()}";
-    }
-}
diff --git a/src/Hl7.Fhir.Shims.Base/Hl7.Fhir.Shims.Base.projitems b/src/Hl7.Fhir.Shims.Base/Hl7.Fhir.Shims.Base.projitems
index 3f434107e1..33224d0137 100644
--- a/src/Hl7.Fhir.Shims.Base/Hl7.Fhir.Shims.Base.projitems
+++ b/src/Hl7.Fhir.Shims.Base/Hl7.Fhir.Shims.Base.projitems
@@ -9,6 +9,7 @@
     <Import_RootNamespace>Hl7.Fhir.Shims.Base</Import_RootNamespace>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="$(MSBuildThisFileDirectory)Specification\Source\SnapshotSource.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Specification\Terminology\ExpandParameters.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Specification\Terminology\ExternalTerminologyService.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Specification\Terminology\FallbackTerminologyService.cs" />
diff --git a/src/Hl7.Fhir.Shims.Base/Hl7.Fhir.Shims.Conformance.shproj b/src/Hl7.Fhir.Shims.Base/Hl7.Fhir.Shims.Base.shproj
similarity index 100%
rename from src/Hl7.Fhir.Shims.Base/Hl7.Fhir.Shims.Conformance.shproj
rename to src/Hl7.Fhir.Shims.Base/Hl7.Fhir.Shims.Base.shproj
diff --git a/src/Hl7.Fhir.Conformance/Specification/Source/SnapshotSource.cs b/src/Hl7.Fhir.Shims.Base/Specification/Source/SnapshotSource.cs
similarity index 100%
rename from src/Hl7.Fhir.Conformance/Specification/Source/SnapshotSource.cs
rename to src/Hl7.Fhir.Shims.Base/Specification/Source/SnapshotSource.cs