OSI could run over X.25. As you say, it doesn't mandate dumb terminals. I worked for a couple of startups that ran services over X.25. One road not taken could

OSI could run over X.25. As you say, it doesn't mandate dumb terminals. I worked for a couple of startups that ran services over X.25. One road not taken could have been to define a structured document format in ASN.1 that would be displayed by the terminal.