Charset selection
=================

   As it is setup now, the program assumes that the input file is coded
using 8-bit ISO 8859-1 code, also known as Latin-1 character set,
*unless* if it is compiled for MS-DOS, in which case it uses the
character set of the IBM-PC.  (GNU `ptx' is not known to work on
smaller MS-DOS machines anymore.)  Compared to 7-bit ASCII, the set of
characters which are letters is then different, this fact alters the
behaviour of regular expression matching.  Thus, the default regular
expression for a keyword allows foreign or diacriticized letters.
Keyword sorting, however, is still crude; it obeys the underlying
character set ordering quite blindly.

`-f'
`--ignore-case'
     Fold lower case letters to upper case for sorting.