The regexp:match function lets you get hold of the substrings of the
string passed as the first argument that match the captured parts of
the regular expression passed as the second argument.
The second argument is a regular expression that follows the Javascript
regular expression syntax.
The third argument is a string consisting of character flags to be used
by the match. If a character is present then that flag is true. The
flags are:
g: global match - the submatches from all the matches in the string
are returned. If this character is not present, then
only the submatches from the first match in the
string are returned.
i: case insensitive - the regular expression is treated as case
insensitive. If this character is not present,
then the regular expression is case sensitive.
The regexp:match function returns a node set of 'match' elements, each of
whose string value is equal to a portion of the first argument string
that was captured by the regular expression. If the match is not global,
the first match element has a value equal to the portion of the string
matched by the entire regular expression.