coreutils: Charset selection in ptx

1 
1 7.5.2 Charset selection
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1 
1 As it is set up now, the program assumes that the input file is coded
1 using 8-bit ISO 8859-1 code, also known as Latin-1 character set,
1 _unless_ it is compiled for MS-DOS, in which case it uses the character
1 set of the IBM-PC.  (GNU ‘ptx’ is not known to work on smaller MS-DOS
1 machines anymore.)  Compared to 7-bit ASCII, the set of characters which
1 are letters is different; this alters the behavior of regular expression
1 matching.  Thus, the default regular expression for a keyword allows
1 foreign or diacriticized letters.  Keyword sorting, however, is still
1 crude; it obeys the underlying character set ordering quite blindly.
1 
1 ‘-f’
1 ‘--ignore-case’
1      Fold lower case letters to upper case for sorting.
1