Library /sys$common/syshlp/lse$clihelp.hlb Features, Placeholders, Nonterminal Placeholders  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  If the current position is on  a  nonterminal  placeholder  when  the
  EXPAND  key  is  pressed,  the  Editor  deletes  the  placeholder and
  replaces it with the text of the placeholder body.