When I retired from IBM Italy, I decided not to abandon Information Technology altogether but to keep current on new areas, which at the time included the Internet and its websites.
Initially, this involved learning a new "language" (HTML) so I bought a little manual on it and, to my delight, I discovered that I already knew its syntax and tags .
In the mid-1990s our Education department decided that thenceforth our course manuals should be produced in-house and no longer by outside printers. We were directed to learn a mainframe application called Script/VS from the 1980s, the main component of IBM's Document Composition Facility (DCF) using a Generalized Markup Language (GML), and fortunately shortly later a much simpler version called Bookmaster.
The formatted text files thus produced would then be printed on an IBM 3800, the first commercially available laser printer using continuous forms:
What had probably happened was that at the international committee working on the specifications for web pages IBM, then an authoritative and influential member, argued that displaying pages on a screen was really like "printing" them and its GML had already been in use by major publishing houses for years, thus it could very well be used as the basis for the Hyper-Text Mark-up Language (HTML) rather than inventing something new.
My current 'professional' activities include: