need syntax of ksh substring builtin

[A DeSimone]

OK, I give up.  Can someone (anyone) *please* tell me what the
syntax is of the Korn shell's builtin substring function?  For some
unknown reason it's missing from the man pages I have.  It is mentioned
in the memo I have by D.G. Korn but its usage is not detailed.  Trial and
error just didn't resolve my ignorance.  HELP! (Thanks a lot.)

PS: no need to clutter the net with a posting; email would be fine.
-- 

  Alex DeSimone, Amala Consultants @ Bell Communications Research
  ..!{ihnp4,allegra}!rruxc!alex

** Disclaimer?  I don't need no stinkin' disclaimer! **