Taken bits from Andy's PR (seen too late).

Author: CBenghi

ids-lib/IfcSchema/IfcSchemaVersionsExtensions.cs

@@ -23,6 +23,11 @@ public static class IfcSchemaVersionsExtensions
 	/// Canonical string version of the schema version
 	/// </summary>
 	public const string IfcSchema4x3String = "IFC4X3_ADD2";
+	
+	/// <summary>
+	/// Legacy string version of the IFC4X3 schema version
+	/// </summary>
+	public const string IfcSchema4x3StringLegacy = "IFC4X3";
 
 	/// <summary>
 	/// Converts a set of IFC schema name strings to the relative enum value
@@ -39,6 +44,7 @@ public static IfcSchemaVersions GetSchema(IEnumerable<string> schemaStrings)
 				IfcSchema2x3String => IfcSchemaVersions.Ifc2x3,
 				IfcSchema4String => IfcSchemaVersions.Ifc4,
 				IfcSchema4x3String => IfcSchemaVersions.Ifc4x3,
+				IfcSchema4x3StringLegacy => IfcSchemaVersions.Ifc4x3,
                 _ => IfcSchemaVersions.IfcNoVersion,
             };
             if (v == IfcSchemaVersions.IfcNoVersion)