File Retrieval and Editing System follows Hypertext Editing System
The File Retrieval and Editing SyStem, or FRESS, was a hypertext system developed at Brown University starting in 1968 by Andries van Dam and his students, including Bob Wallace.  It was the first hypertext system to run on readily available commercial hardware and OS.  It is also possibly the first computer-based system to have had an "undo" feature for quickly correcting small editing or navigational mistakes.Features
FRESS was a continuation of work done on van Dam's previous hypertext system, HES, developed the previous year. FRESS ran on an IBM 360-series mainframe running VM/CMS.  It improved on HES's capabilities in many ways, inspired by Douglas Engelbart's NLS.  FRESS implemented one of the first virtual terminal interfaces, in order to provide device-independence.  It could run on various terminals from dumb typewriters up to the Imlac PDS-1 graphical minicomputer. On the PDS-1, it supported multi-window WYSIWYG editing and graphics display. The PDS-1 used a light pen, not a mouse, and the light pen could be "clicked" using a foot-pedal.
FRESS allowed multiple users to collaborate on as set of documents, which could be of arbitrary size, and (unlike prior systems) were not laid out in lines until the moment of display. FRESS users could insert a marker at any location within a text document and link the marked selection to any other point either in the same document or a different document.  This was much like the World Wide Web of today, but without the need for the anchor hyperlinks that HTML requires.  Links were also bi-directional, unlike in today's web.FRESS had two types of links: tags and "jumps". Tags were links to information such as references or footnotes, while "jumps" were links that could take the user through many separate but related documents. FRESS also had the ability to assign keywords to links or text blocks to assist with navigation. Keywords could be used to select which sections to display or print, which links would be available to the user, and so on. Multiple "spaces" were also automatically maintained, including an automatic table of contents and indexes to keywords, document structures, and so on.  Users could view a visualization of the "structure space" of the texts and cross-reference links, and could directly rearrange the structure space, and automatically update the links to match.FRESS was essentially a text-based system and editing links was a fairly complex task unless you had access to the PDS-1 terminal, in which case you could select each end with the lightpen and create a link with a couple of keystrokes. FRESS provided no method for knowing where the user was within a collection of documents.