A transclusion is the virtual inclusion of a piece of one document in another. Rather like a mechanical book (Pop-up BookTM), from one page the audience can see through a sort of window onto a segment of another page. This makes it possible for academics and creators to simply and efficiently re-use material. Currently, the Web requires a document be wholly referred to, but by making it possible to virtually include only a piece, people are less likely to retype in the quoted section, and thereby make available the added facility of readers being able to follow the quote to its original should they so choose.

Transclusions are a very important feature in order to make fair charging systems available on the Internet in the future. If a tiny charge is attached to each segment of a document, as a person receives segments they are charged for each individual segment, then the payments can be fairly allocated to those who created the delivered segments. This is covered in much of Ted Nelson's work on the Xanadu Project [Nel94].

Transclusions can also be useful for personal use. I frequently write papers that involve overlapping material. I, therefore, would like to interlink these papers and re-use only specific paragraphs, graphs and tables. This is currently only possible with HTML if my documents are sharing images, and even then it is not possible to go from these images to the various complete papers in which they virtually reside. What I find myself doing is cutting the segments I need out of a document and creating whole extra pages to which I make links, thus filling up my hard drive with redundancies. Perhaps the work of Polle T. Zellweger, Bay-Wei Chang, and Jock D. Mackinlay, on "Fluid Links for Informed and Incremental Link Transitions" as presented at ACM Hypertext 98 [ZCM98] may prove helpful in finally developing the transclusion.