NAME =BACK
0000 back:	$=0   body;    Regular PTRAN Definition
0004		$=1   ;        NOP (comment)
0006		$=2   + f;     Handle filename in NAME=<filename>
000A		      e        Error
000B body:	      d + < EMIT(80) mark + alt > c rep.alt `
001A mark:	      XOR(40) hex .
001F alt:	      suc :alt
0023 suc:	$=0   opt.prim;
0027		$=1   prim .
002B opt.prim:	      EMIT(20) prim rep.prim end .
0034 rep.prim:	      prim :rep.prim
0038 prim:	$=0   hex ;
003C		$=1   g + ;
0040		$=2   h + ;
0044		$=3   i + ;
0048		$=4   a + .
004C end:	$=0   EMIT(20);
0050		$=1   EMIT(7F) .
0054 rep.alt:	      < EMIT() sep + alt > c :rep.alt
005F sep:	$=1   XOR(40) .
0063 hex:	+ b ++ bb.
006A bb:	b ++ :bb