[NTG-context] Back in the 90s

Hello, I was reading about the history of ConTeXt in the Not So Short Introduction To ConTeXt and I have a historical question. I noticed that the PDF specification was published in 1993 yet ConTeXt was invented in 1991. The book suggests that PDF output was handled by the PdfTeX engine in MKII in 2005. What sort of output did the software produce before PdfTeX was introduced? Was this the same as the output produced by the software before the publication of the PDF specification? Kind regards, Riviera she, her, hers https://wiki.contextgarden.net/User:River