The Meta-Content Format/Framework
MCF is a technology dating from 1996-7 that has now been superseded by the Resource Description Framework. This is an archive of material about it for historical reference. See also Tim Bray's history of RDF for information on how the transition happened.
Apple's HotSauce Technology ("Project X")
HotSauce, or Project X, was software from Apple that let you fly through MCF documents in 3D.
See also: Technophobe's Guide to Site Saucing.