I do think it was influenced by troff, since they do bear some visual similarities. A little googling didn't find what it was, but I do believe it was directly related to this: http://www.sngx2.com.br/Help/Epson%20ESC-P2%20Printer%20Comm...

Except that the escape was replaced by a dot for the driver that converted it, and more "user friendly" formats like title (which was centered, bold and underlined). But I'm literally guessing since it was so long ago.