contain any combination of word (C<\w>) characters, SPACE (U+0020),
HYPHEN-MINUS (U+002D), LEFT PARENTHESIS (U+0028), RIGHT PARENTHESIS (U+0029),
and NO-BREAK SPACE (U+00A0). These last three should never have been allowed
-in names, and are retained for backwards compatibility only; they may be
+in names, and are retained for backwards compatibility only; NO-BREAK SPACE IS
+currently deprecated and scheduled for removal in Perl v5.26; the other two
+may also be
deprecated and removed in future releases of Perl, so don't use them for new
names. (More precisely, the first character of a name you specify must be
something that matches all of C<\p{ID_Start}>, C<\p{Alphabetic}>, and