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Re: operational definition of transclusion

Erich Schneider wrote:
> Hi, Andrew. This is Erich Schneider - we met at HT '97 in Southampton.
> I was wondering if you could tell me if the following is correct as a
> description of how transclusion is supposed to operate:
> Documents can contain transclusions of regions in other documents.
> When a document containing a transclusion is viewed, the region being
> transcluded is fetched from its source; if that region contains
> transclusions itself, those regions are fetched, etc. The transcluded
> region is then displayed as if it were part of the original document
> being viewed, but some mechanism is available for fetching the
> transcluded region's source document.

This is a pretty good description of how the "text transclusion" proposal
for HTML is supposed to operate, but that is a kludge due to the
limitations of HTML.  In the normal case, a transclusion is an identic
relationship where the same material is addressed (by reference) from
multiple contexts.  When constructing a new context (document), you can
transclude material from any source, but you always construct a new set
of references to the original source material ("primedia").  References
to references are never used, thus simplifying many technical issues.

In the Xanadu designs, transclusions are bivisible just like links; you
can see every context in which any given primedia is used.  In fact,
transclusions and links are closely related - transclusions connect
instances of identical content, while links connect instances of different
but somehow related content.  From an implementation standpoint, links
can be implemented as a special case of transclusions or vice versa.

Share and enjoy,
		*** Xanni ***
mailto:xanni@xxxxxxxxxx                         Andrew Pam
http://www.xanadu.net/xanadu/                   Technical VP, Xanadu
http://www.glasswings.com.au/                   Technical Editor, Glass Wings
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