Why a site-lisp directory in /usr/local/share/emacs/22.0.50/

[stefano.sabatini-lala@poste.it]

I'm trying to figure out how the load-path is formed, and the
documentation isn't very clear.

The default load-path should consist initially only by the directories:

<prefix>/share/emacs/site-lisp
for all the not-flavour-specific libraries, and
<prefix>/share/emacs/<flavour>
for all the flavour-specific libraries.

<prefix> is the value of the variable "prefix" defined in the emacs
Makefile (usually /usr/local/ for a local install).

So I don't understand why there is a site-lisp directory:
/usr/local/share/emacs/22.0.50/site-lisp

(which is actually empty), in the default flavour libraries dir
(/usr/local/share/emacs/22.0.50).

Is it simply some backward-compatible-messy-thing (I can happily delete
it) or is something that actually makes sense?

Thanks.