Based on submission from E Choroba in RT # 131603.
space interpretation within a single multi-character construct. For
example in C<\x{...}>, regardless of the C</x> modifier, there can be no
spaces. Same for a L<quantifier|/Quantifiers> such as C<{3}> or
space interpretation within a single multi-character construct. For
example in C<\x{...}>, regardless of the C</x> modifier, there can be no
spaces. Same for a L<quantifier|/Quantifiers> such as C<{3}> or
-C<{5,}>. Similarly, C<(?:...)> can't have a space between the C<"{">,
+C<{5,}>. Similarly, C<(?:...)> can't have a space between the C<"(">,
C<"?">, and C<":">. Within any delimiters for such a
construct, allowed spaces are not affected by C</x>, and depend on the
construct. For example, C<\x{...}> can't have spaces because hexadecimal
C<"?">, and C<":">. Within any delimiters for such a
construct, allowed spaces are not affected by C</x>, and depend on the
construct. For example, C<\x{...}> can't have spaces because hexadecimal