There never was one, which is the point. Compuserve had a weird compiled binary format. AOL had a similarly weird proprietary format, Prodigy was a vector based

There never was one, which is the point. Compuserve had a weird compiled binary format. AOL had a similarly weird proprietary format, Prodigy was a vector based system that could never work with anyone else, and there were countless others (Genie, etc). Meanwhile, HTML came along over PPP, and that's when the entirety of corporate america, and residential dial-up users joined the network. The same thing is happening now with the mobile payments industry.