[TriLUG] [OT] "Usage:" syntax?

[Tom Roche]

Gurus: where is the syntax of "Usage:" strings documented?

For past scripts I've always done "Usage:" strings by copying one from
the manpage of a command that behaves sorta like my script. However
now I'm doing a script for which I can't find a useful exemplar;
besides, I'd just like to have a reference. Apologies if this is a
FAQ, but I've tried a buncha google strings to no avail.

seeking enlightenment, Tom Roche <Tom_Roche at pobox.com>