+=item Ranges of ASCII printables should be some subset of "0-9", "A-Z", or
+"a-z" in regex; marked by S<<-- HERE> in m/%s/
+
+(W regexp) (only under C<S<use re 'strict'>> or within C<(?[...])>)
+
+Stricter rules help to find typos and other errors. Perhaps you didn't
+even intend a range here, if the C<"-"> was meant to be some other
+character, or should have been escaped (like C<"\-">). If you did
+intend a range, the one that was used is not portable between ASCII and
+EBCDIC platforms, and doesn't have an obvious meaning to a casual
+reader.
+
+ [3-7] # OK; Obvious and portable
+ [d-g] # OK; Obvious and portable
+ [A-Y] # OK; Obvious and portable
+ [A-z] # WRONG; Not portable; not clear what is meant
+ [a-Z] # WRONG; Not portable; not clear what is meant
+ [%-.] # WRONG; Not portable; not clear what is meant
+ [\x41-Z] # WRONG; Not portable; not obvious to non-geek
+
+(You can force portability by specifying a Unicode range, which means that
+the endpoints are specified by
+L<C<\N{...}>|perlrecharclass/Character Ranges>, but the meaning may
+still not be obvious.)
+The stricter rules require that ranges that start or stop with an ASCII
+character that is not a control have all their endpoints be the literal
+character, and not some escape sequence (like C<"\x41">), and the ranges
+must be all digits, or all uppercase letters, or all lowercase letters.
+
+=item Ranges of digits should be from the same group in regex; marked by
+S<<-- HERE> in m/%s/
+
+(W regexp) (only under C<S<use re 'strict'>> or within C<(?[...])>)
+
+Stricter rules help to find typos and other errors. You included a
+range, and at least one of the end points is a decimal digit. Under the
+stricter rules, when this happens, both end points should be digits in
+the same group of 10 consecutive digits.
+