LFUN
  protected mixed _del_id (mixed *prop, mixed str)

DESCRIPTION
  Remove one or more strings from an array.

  Arguments:
    prop: the array to remove the strings from (may be 0).
    str : the string or string array to add.

  Result:
    The given <prop> array without <str>.

  The function just works on arrays created by _add_id().

  This is an auxiliary function used in maintaining P_IDS, P_ADS,
  P_CLASS_IDS and P_CLASS_ADS and should not be called by hand.

IMPLEMENTED
  /std/thing/description