This article is a very concise description not only of enabling the HP-UX NFS server, but also configuring it and testing it.
However, it is for HP-UX 11.23 (11i v2); the current version is 11.31 (or 11i v3). Things may be slightly different with 11i v3.
UNIX Administratosphere 
11.31 is different. It took awhile to get used to the share command.
The share command comes from Unixware and Solaris; I’ve never found it to make much sense. The “old” way of using /etc/exports worked just fine, and the amd automounter also fit in just right. But Sun didn’t use amd either.
I agree with ddouthitt, and can only imagine the share change due to new more secure versions of NFS