Precise definition of hostname

[Fred Houlihan]

I'm looking for a precise definition of hostname, not in an NIS or yp
sense, nor that of sendmail, but from the perspective of the result
returned by the hostname command in a stand-alone environment.

Specifically, if I have a host on the internet with the name
aster.psu.edu, when I issue the hostname command what exactly should I
see?

This may seem like a trivial request but it actually has become a
subject of debate here.  Any references on this topic would also be
greatly appreciated.

Thanks, Fred Houlihan