STR$FIND_FIRST_IN_SET

   The Find First Character in a Set of Characters 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_IN_SET returns
   the position of the first character in the string that matches
   any of the characters in the selected set of characters.

   Format

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

Additional information available:

Returns         Arguments