diff --git a/Xbim.InformationSpecifications.NewTests/Xbim.InformationSpecifications.Tests.csproj b/Xbim.InformationSpecifications.NewTests/Xbim.InformationSpecifications.Tests.csproj
index 6b4f439..8ee8ba4 100644
--- a/Xbim.InformationSpecifications.NewTests/Xbim.InformationSpecifications.Tests.csproj
+++ b/Xbim.InformationSpecifications.NewTests/Xbim.InformationSpecifications.Tests.csproj
@@ -17,13 +17,13 @@
 
   <ItemGroup>
     <PackageReference Include="FluentAssertions" Version="6.12.0" />
-    <PackageReference Include="ids-lib" Version="1.0.43" />
+    <PackageReference Include="ids-lib" Version="1.0.47" />
     <PackageReference Include="MartinCostello.Logging.XUnit" Version="0.3.0" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="7.0.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
     <PackageReference Include="NSubstitute" Version="5.1.0" />
-    <PackageReference Include="xunit" Version="2.5.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.1">
+    <PackageReference Include="xunit" Version="2.5.3" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.3">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
diff --git a/Xbim.InformationSpecifications.NewTests/buildingSmartCompatibility.cs b/Xbim.InformationSpecifications.NewTests/buildingSmartCompatibility.cs
index 81fbc69..f069fe0 100644
--- a/Xbim.InformationSpecifications.NewTests/buildingSmartCompatibility.cs
+++ b/Xbim.InformationSpecifications.NewTests/buildingSmartCompatibility.cs
@@ -104,8 +104,8 @@ public void CanReadIdsSamples(string idsFile)
             f.Exists.Should().BeTrue("test file must be found");
                 
             var loggerMock = Substitute.For<ILogger<BuildingSmartCompatibilityTests>>(); // this is to check events
-            var x = LoadBuildingSmartIDS(f.FullName, loggerMock);
-            x.Should().NotBeNull();
+            var loadedIds = LoadBuildingSmartIDS(f.FullName, loggerMock);
+            loadedIds.Should().NotBeNull();
 			var errorAndWarnings = loggerMock.ReceivedCalls().Where(call => call.IsErrorType(true, true, true));
 			errorAndWarnings.Should().BeEmpty();
         }
diff --git a/Xbim.InformationSpecifications/Facets/buildingSMART/PartOfFacet.cs b/Xbim.InformationSpecifications/Facets/buildingSMART/PartOfFacet.cs
index 6ae3413..f3eb36c 100644
--- a/Xbim.InformationSpecifications/Facets/buildingSMART/PartOfFacet.cs
+++ b/Xbim.InformationSpecifications/Facets/buildingSMART/PartOfFacet.cs
@@ -200,7 +200,10 @@ public PartOfRelation GetRelation()
         /// <param name="value"></param>
         public void SetRelation(PartOfRelation value)
         {
-            EntityRelation = value.ToString();
+            if (value == PartOfRelation.Undefined)
+                EntityRelation = string.Empty;
+            else
+                EntityRelation = value.ToString();
         }
 
         /// <summary>
diff --git a/Xbim.InformationSpecifications/IO/Xids.Io.xml.cs b/Xbim.InformationSpecifications/IO/Xids.Io.xml.cs
index d434658..c19d3d7 100644
--- a/Xbim.InformationSpecifications/IO/Xids.Io.xml.cs
+++ b/Xbim.InformationSpecifications/IO/Xids.Io.xml.cs
@@ -265,12 +265,17 @@ private static void ExportBuildingSmartIDS(IFacet facet, XmlWriter xmlWriter, bo
                 case PartOfFacet pof:
                     xmlWriter.WriteStartElement("partOf", IdsNamespace);
                     WriteFacetBaseAttributes(pof, xmlWriter, logger, forRequirement, requirementOption);
-                    xmlWriter.WriteAttributeString("relation", pof.EntityRelation.ToString());
+                    if (pof.GetRelation() != PartOfFacet.PartOfRelation.Undefined)
+                        xmlWriter.WriteAttributeString("relation", pof.GetRelation().ToString().ToUpperInvariant()); 
                     if (pof.EntityType is not null)
                     {
                         // todo: review the forRequirement parameter here
                         ExportBuildingSmartIDS(pof.EntityType, xmlWriter, false, logger, context, null);
                     }
+                    else
+                    {
+                        logger?.LogError("Invalid null EntityType in partOf facet for buildingSmart requirements.");
+                    }
                     xmlWriter.WriteEndElement();                    
                     break;
                 default:
@@ -542,8 +547,16 @@ static private void WriteFacetBaseElements(FacetBase cf, XmlWriter xmlWriter)
             }
             else
             {
-                var main = XElement.Parse(File.ReadAllText(fileName));
-                return LoadBuildingSmartIDS(main, logger);
+                try
+                {
+                    var main = XElement.Parse(File.ReadAllText(fileName));
+                    return LoadBuildingSmartIDS(main, logger);
+                }
+                catch (Exception ex)
+                {
+                    logger?.LogError(ex, $"{ex.Message}");
+                    return null;
+                }
             }
         }
 
diff --git a/Xbim.InformationSpecifications/Xbim.InformationSpecifications.csproj b/Xbim.InformationSpecifications/Xbim.InformationSpecifications.csproj
index 133eaa5..db47e4e 100644
--- a/Xbim.InformationSpecifications/Xbim.InformationSpecifications.csproj
+++ b/Xbim.InformationSpecifications/Xbim.InformationSpecifications.csproj
@@ -19,7 +19,7 @@
 		<AssemblyName>Xbim.InformationSpecifications</AssemblyName>
 		<RootNamespace>Xbim.InformationSpecifications</RootNamespace>
 		<!-- Remember to update the hardcoded AssemblyVersion property in XIDS-->
-		<AssemblyVersion>0.3.43</AssemblyVersion>
+		<AssemblyVersion>0.3.44</AssemblyVersion>
 		<!-- Remember to update the hardcoded AssemblyVersion property in XIDS-->
 		<FileVersion>$(AssemblyVersion)</FileVersion>
 		<Version>$(AssemblyVersion)</Version>
@@ -49,7 +49,7 @@
 		<None Include="C:\Data\Dev\XbimPrivate\Xbim.Xids\Xbim.InformationSpecifications\.editorconfig" />
 	</ItemGroup>
 	<ItemGroup>
-    <PackageReference Include="ids-lib" Version="1.0.43" />
+    <PackageReference Include="ids-lib" Version="1.0.47" />
     <PackageReference Include="Nullable" Version="1.3.1">
 	    <PrivateAssets>all</PrivateAssets>
 	    <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
diff --git a/Xbim.InformationSpecifications/Xids.AssemblyVersion.cs b/Xbim.InformationSpecifications/Xids.AssemblyVersion.cs
index 91bf5c0..1928090 100644
--- a/Xbim.InformationSpecifications/Xids.AssemblyVersion.cs
+++ b/Xbim.InformationSpecifications/Xids.AssemblyVersion.cs
@@ -7,6 +7,6 @@ public partial class Xids
         /// This is useful for environments that do not allow to load information from the DLL dynamically
         /// (e.g. Blazor).
         /// </summary>
-        public static string AssemblyVersion => "0.3.43";
+        public static string AssemblyVersion => "0.3.44";
     }
 }