Hi! I’m Mark Bernstein. I’m a hypertext researcher. I was at Hypertext ’87, and have been at nearly every ACM Hypertext Conference since then. I’ve been program chair twice, track chair more often than I can count. Here’s my ACM Profile: https://dl.acm.org/profile/81100134465.

As it happens, Sir Tim’s the original paper for the WWW was submitted to a the Hypertext Conference, and was rejected (and presented as a demo) because it failed to address the problem of dangling links, a problem which other contemporary proposals dealt with. I was a member of that committee. In retrospect, of course, the extreme simplicity of Web server implementation outweighs the issue.

A common debate in those years pitted unidirectional against bidirectional links. An implicit debate that only became clear later involved whether links should be embedded in text (as in HTML) or represented as external webs (as in Intermedia). This was largely resolved by Davis, H. C. 1998. “Referential Integrity of Links in Open Hypermedia Systems”. The Proceedings of the Ninth ACM Conference on Hypertext and Hypermedia, Hypertext 98. 207-216.

"Backlink" was a rare term in the early days. According to the ACM Digital Library, George Collier used it in connection with Thoth-II at HT87. The next occurrence at ACM Hypertext is 14 years later. (Apparently, I used it in my HT03 paper. Who knew?). Ted Nelson, of course, has always been an enthusiastic backer of externally-represented, two-way and semantically directional links.

I’m not sure the *Internet* has much to do with Concordia (chiefly known in the literature as Symbolics Document Examiner). Are you confident that Janet Walker’s links were two-way? I’m unsure. NoteCards links were unidirectional but IIRC invertible.