Transclusion means "freedom of redundancy". If a page is transcluded in several other pages, and it is updated, the updates propagate automatically to all includes in a synchronization transaction (hot update).
Ted Nelson defined transclusion as the central concept behind hypertext and hypermedia:
Transconsistency is a transclusion-related concept which allows for transformations of the page before it is embedded. Web systems are usually transclusive
Andreas Bartho's PhD on Elucidative Modeling employed transclusion and transconsistency for
redundancy-reduced documentation. The technique generates parts of the documentation from models and code.