[CSS2.1 - Grammar] The clip property with rect function, allows combination of spaces and commas?

CSS 2.1 standards supported grammar
    clip: rect(96px, 96px, 96px, 96px);

CSS 2.1 backwards compatible supported grammar
    clip: rect(96px 96px 96px 96px);

CSS 2.1 fuzz test variation with lack of cross browser parity
    clip: rect(96px  ,96px 96px,  96px);

The tests and verification I wanted to perform were (FireFox 3 B2 was used when finding the discrepancy):

1.       Does arbitrary whitespace matter between tokens or is it well ignored. (All: yes)

2.       Since I support commas and I support spaces can I support a mixture? (FireFox: yes, Safari and Opera: no)

3.       Out of range parsing (less/more than 4 dimensions). (All: yes)

So the clarification needs to be on the item 2 where we mix and match commas and spaces as delimiters. Should the standards behavior be that of FireFox or Safari/Opera?

Justin [MSFT]