Hi Arnold, So, Texinfo @parts do not map to Docbook. Not surprising. Such is life. To get parts in your Docbook output, all I can think of is the useless "hack it in by hand" approach (e.g., throw comments into the source and post-process them to create the necessary <part>/related elements). Sorry.
I created the Texinfo @part command as independent from the sectioning structure because it had to be that way for compatibility, etc. Creating a second kind of part command that *is* part of the sectioning structure sounds like an awful lot of work for no essential gain. Best, k