Design details and usage requirements should be pushed into the "Remarks" section of the two APIs. https://learn.microsoft.com/dotnet/api/system.runtime.interopservices.typemapassociationattribute-1 https://learn.microsoft.com/dotnet/api/system.runtime.interopservices.typemapattribute-1 The design details can be found at https://github.com/dotnet/runtime/blob/main/docs/design/features/typemap.md.