stills leaves the issue of how to print out something that doesn't exist as a physical old style physical type face character. (way pre-dot matrix / laster printer stuff). -- aka substituting 3 characters way more informative than blank space.
My (possibly wrong) understanding is that trigraphs were a late addition to the ANSI standard, which would place it in late 80s, well into the CRT terminal and dot-matrix era.
