@awb the man page sources are in XML now, using a customized DocBook DTD, much like the DTD used with SGML, from which we generate nroff, html, & PDF output, but only the nroff output is shipped with the OS now. We do the XML->nroff conversion once at build time, instead of every time a user runs the man command as was done in the SGML days.
Answerbook is gone now, replaced by a web browser and https://docs.oracle.com/en/operating-systems/solaris/oracle-solaris/ (and docs.sun.com before that).