... Let's remove the markup so we can see what this is about in plain
text:
> This means you can write things like \x{ FFFC } if you
> like. This applies to all such constructs, namely \b{}, \g{},
> \k{}, \N{}, \o{}, and \x{}; as well as the regular
> expression quantifier {m,n}. \p{} and \P{} retain their
> already-existing, even looser, rules mandated by the Unicode standard
> (see perluniprops/Properties accessible through \p{} and \P{}).
>
> This ability is in effect regardless of the presence of the /x
> regular expression pattern modifier.
>
> Additionally, the comma in a regular expression braced quantifier may
> have blanks (tabs or spaces) before and/or after the comma, like
> qr/a{ 5, 7 }/.
Is that better?
It just means that spaces can appear inside those regular expression
construct that use curly brackets.
--
Ben.