Transclusion

In computer science, 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 has a limited form of transclusion. For instance, it's possible to refer to an image, which the web browser will retrieve and draw on the page; see chipmunk for an example. Also, a document can contain an "iframe," or inline frame, that refers to another document. As of January 2002, Weather.com uses this technique to build its weather forecast page from several small documents. Future versions of HTML may support deeper transclusion of portions of documents referenced through XML's XPath.

Can anybody describe the copyright implications of "framing" with respect to transclusion?

The pracice of including data from other sites, such as links to images, etc., is something usually frowned upon because of the use of bandwidth and computing power required from the remote computer system.

A side note

There are other technologies that have similar abilities of including extenal components such as ASP (active server pages), JSP (java server pages), and the use of SSI (server-side includes).