Use of s00

[Peter Blomberg]

Are s00 allowed for non-assembly parts as a regular subpart? I thought subpart numbering starts from 01.

[Gerald Lasser]

In most cases s00 came into play when a (subfile) part was official for some time and then got a print, the file without the concerned surfaced got s00.
So I would say it is not a regular case more a way to get a "low" number for such subfiles. 
A recent example is the C3PO head, which was not very efficiently organised

[Philippe Hurbain]

It's well known that integers start at 0... More seriously, nothing precludes its usage. I use it often as the top level subpart containing everything but the paternable areas.