Sorry for digging up an old topic, but I've tried to parse the format out per the Mach2 PDF posted above (from the archive.org historical cache, as the file 404'd on machsupport.com). My parser, I believe, is following the original Mach2 spec, but it's still throwing some pretty wild errors when it encounters strings longer than 255 bytes, which shouldn't be possible according to the old spec. It seems quite common, however, for newer screens to use > 256 chars for visual basic macros.
My question is, is there a later version of this document that explains how strings > 256 chars are handled? is there an escape sequence?