Is there any documentation of the .skp file format?

I think it could be useful to, e.g., verify contributions to sombeody’s library :wink: or, as @sjdorst asked, inspect group and DC attributes. If you meant specifically the YAML aspect, I mentioned that simply because of ready-made library support for reasonably human-readable formatting of structured data.

Your example is quite nicely formatted. To address the original request, can your code show the model entities’ attributes yet (short of entire geometry) and would you be able to share it?