Temporal versioning of XML documents

A data model supporting the unification of the management of temporal XML document databases and version control, i.e., a Temporal Version Data Model (TVDM), is proposed. TVDM is temporally change-centric and represents the change between two consecutive versions by means of temporal delta (tDelta). A tDelta employs a temporal XML expression (tXex) which is an extension of ordinary XML elements by incorporation into them temporal as well as ordinary variables. In addition to valid time, TVDM introduces version time and associates it with each version. All versions including the base or the current one can be uniformly represented by tDeltas. A technique to implement TVDM is also presented.