Alphacam后处理解释，用于适配自己机床的后处理说明
START
$10文件主要行
$12 "程式开头" Main Program LEADING lines
$15 "程式结尾" Main Program TRAILING lines
$17 "档案结尾" File TRAILING Lines
$20 "XY轴快速位移" Rapid Move in XY (MILL/ROUTER/FLAME/LASER) or XZ (LATHE) only