Nope, not really, but most times it's rather consistent. Most manuals would list optional arguments with square brackets (
[foo]), mandatory ones with angle brackets or no brackets at all (
baz, latter one often underlined).
Also, in almost all cases if the number of arguments is variable, you'll have some kind of list (as you mentioned,
[quux ...] or
[quux[, quux[...]]] ...), where similarly
[quuz] most of the times denotes exactly one argument. In rare cases,
[quuz] could also mean »one or more arguments«, but most manuals conform to the ellipsis of listing form.
It's a quasi standard, but you couldn't definitely rely on it. But in my experience it's okay in 95% times.
Point is, there are hundreds of software vendors of any couleur out there, not only »big players« but there's also software written by single individuals that proofed to be useful. All of them (hopefully) write their manpages in some individual way… most of them know long enough to take care of common conventions, but there are also ones who don't care or have some kind of mental defect concerning style taste etc. ;)