Solaris 10, SPARC.
While trying clean up my "/opt" directory, I saw the "sun_docs" directory.
I scanned the contents with "du -a", and also found a single, possibly related file (/var/opt/sun_docs/sundocs.html).
If I understand correctly, it looks like a local set of HTML files, designed to be ready by a locally running browser? It looks like it could be shared via http, if an admin knew how to turn that on.
I did google and check docs.sun.com.