Hypertext/Transclusion

Some hypertext systems, including [Ted Nelson]?'s [Xanadu Project]?, had the capability for documents to include sections of other documents by reference, called transclusion. For example, an article about a country might include a chart or a paragraph describing that country's agricultural exports from a different article about agriculture. Rather than copying the included data and storing it in two places, a transclusion allows it to be stored only once (and perhaps corrected and updated if the link type supported that) and viewed in different contexts. The reference also serves to link both articles.

Present HTML does not have this facility, except in the very limited sense that a whole document can be transcluded in a frame, and a whole graphical image can be transcluded.