Is there a reference document for OOTB SharePoint web part interfaces?

Question

I want my web parts to act as providers and consumers with Out-Of-The-Box (OOTB) SharePoint web parts, including filters.

To design these web parts I need to know the interface of the OOTB web parts, eg. a "Links" web part provides an IWebPartRow, with a Type, URL and Notes.

I can get the information by:

• a web part programmed to interact generically, and display the data it receives
• putting the web parts on a page, and look at the available connections
• inspecting the DLL's (haven't tried this, because I can't find the DLL's, but I guess it's possible)

It seems strange to me that there is no documentation of these interfaces.

Is there a Microsoft document, or a book, which documents the OOTB web parts and filters?