GNU Translate Tables
--------------------

  If you set the `translate' field of a pattern buffer to a translate
table, then the GNU Regex functions to which you've passed that pattern
buffer use it to apply a simple transformation to all the regular
expression and string characters at which they look.

  A "translate table" is an array indexed by the characters in your
character set.  Under the ASCII encoding, therefore, a translate table
has 256 elements.  The array's elements are also characters in your
character set.  When the Regex functions see a character C, they use
`translate[C]' in its place, with one exception: the character after a
`\' is not translated.  (This ensures that, the operators, e.g., `\B'
and `\b', are always distinguishable.)

  For example, a table that maps all lowercase letters to the
corresponding uppercase ones would cause the matcher to ignore
differences in case.(1)  Such a table would map all characters except
lowercase letters to themselves, and lowercase letters to the
corresponding uppercase ones.  Under the ASCII encoding, here's how you
could initialize such a table (we'll call it `case_fold'):

     for (i = 0; i < 256; i++)
       case_fold[i] = i;
     for (i = 'a'; i <= 'z'; i++)
       case_fold[i] = i - ('a' - 'A');

  You tell Regex to use a translate table on a given pattern buffer by
assigning that table's address to the `translate' field of that buffer.
If you don't want Regex to do any translation, put zero into this
field.  You'll get weird results if you change the table's contents
anytime between compiling the pattern buffer, compiling its fastmap, and
matching or searching with the pattern buffer.

  ---------- Footnotes ----------

  (1)  A table that maps all uppercase letters to the corresponding
lowercase ones would work just as well for this purpose.