“Xanalogical literary structure is a unique symmetrical connective system for text (and other separable media elements), with two complementary forms of connection that achieve these functions — survivable deep linkage (content links) and recognizable, visible re-use (transclusion). Both of these are easily implemented by a document model using content lists which reference stabilized media.” (Theodor Holm Nelson – ACM Computing Surveys Hypertext and Hypermedia Symposium)