Procedure error(number: Integer;
                  class: error_class;
                  msg: packed array [lo..hi: integer] of char;
                  param: integer)
  	;
   EXTERNAL;
{*USER*
 
 This is a simple and general error reporting procedure. The contents
of number, msg, and param are up to the caller. When called, a formatted
message is output on the standard output file (OUTPUT), and the pascal
walkback routine is called. If the class is fatal, an exit with status =4
is taken, else return to caller.
 
}