You can add custom properties to your report by calling SetProperties API and retrieve them using the GetProperties API. Or, you can append them inside the report definition (CustomProperties element) but you need to parse the report definition to get them. You can use the RDL Object Model to simplify the latter task.

I think the best part of the publish reports parts process is the ability to capture rich metadata about the report part. Is there a way to create custom metadata, or query additional metadata from the ReportServer database?

Thanks for all your posts, and your book, one of my favorites!