STR$FIND_FIRST_NOT_IN_SET

   The Find First Character That Does Not Occur in Set routine
   searches a string, comparing each character to the characters in
   a specified set of characters. The string is searched character
   by character, from left to right. STR$FIND_FIRST_NOT_IN_SET
   returns the position of the first character in the string that
   does not match any of the characters in the selected set of
   characters.

   Format

     STR$FIND_FIRST_NOT_IN_SET  source-string ,set-of-characters
 

Additional information available:

Returns         Arguments