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Guide was a hypertext system originally developed by Peter J. Brown at the University of Kent in 1982. The original Guide implementation was for Three Rivers PERQ workstations running Unix. The Guide system was also the third hypertext system to be sold commercially, after it was taken over by Office Workstations Ltd. (OWL) in 1984.
Unlike most hypertext systems, the main link mechanism in Guide is based on replacement, meaning that when following a link, the current node breaks open, making room for the destination node. The anchor of the link is replaced by the contents of the destination node. One can close the destination node, which means that it is once again replaced by the text of the anchor. Thus, the basic method of navigation using Guide was the expansion button, in which a section was replaced when selected and in which an expansion would provide additional levels of detail. This allowed the user, whether they were a document author or a reader, to expand and contract a document, viewing the desired level at any time, not unlike viewing methods used in Adobe Acrobat files. Using this method means that the structure of the document must be strictly hierarchical.
Guide supported pop-ups for small annotations, and so-called jumps, which behave like the follow-link operation in most hypertexts (as in van Dam's FRESS system). The jumps allow for the creation of non-hierarchical links.