XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (642 page)

The
piece
A{3}
matches a sequence of exactly three
A
s;
A{3,}
matches a sequence of three or more
A
s, and
A{3,5}
matches a sequence of at least three and at most five
A
s.

By default, quantifiers are greedy—they match as many occurrences of the relevant characters as they can, subject to the regex as a whole succeeding. For example, given the input string
17(c)(ii)
, the regular expression
\(.*\)$
will match the substring
(c)(ii)
. Adding a
?
after the quantifier makes it non-greedy, so the regex
\(.*?\)$
will match the substring
(c)
. This doesn't affect the
matches()
function, which is only concerned with knowing whether or not there is a match, but it does affect
replace()
and
tokenize()
, and XSLT's

, which also need to know which particular characters matched the regex.