CHARNOLIST()
 Lists the characters that do not appear in a string
------------------------------------------------------------------------------
 Syntax

     CHARNOLIST([<cString>]) --> cNotContained

 Argument

     <cString>  Designates the string that is processed.  The default
     value is for an empty string.

 Returns

     CHARNOLIST() returns a character string that contains all characters not
     found in <cString>.

 Description

     This function determines all characters that are not contained in
     <cString>.  The resulting characters might be used as replacement
     characters or for complex deletion procedures.

 Examples

     .  Delete all characters except "XYZ":

        String := "ABXCDYEF"
        ? CHARREM(CHARNOLIST("XYZ"), String)               // "XY"

     .  Generate a list of all 256 ASCII characters:

        ? CHARNOLIST()

     .  To save text to a memo field, all null characters (CHR(0))
        must be exchanged for a character that is not being used:

        cNoList   := CHARNOLIST(cMemoText)
        cNoChar   := SUBSTR(cNoList, 1, 1)
        CHARREPL(CHR(0), @cMemoText, cNoChar)