XIPr is an implementation of XML Inclusions (XInclude) 1.0 in XSLT 2.0. XIPr exists because an include feature had to be provided in an XSLT-based project, and rather than implementing a custom include feature, it was decided to use XInclude. It turned out that there was no available implementation of XInclude in XSLT, so we decided to create one. XIPr is a fully conforming XInclude implementation, but it is only minimally conformant, which means that it only supports the XML Pointer Language (XPointer) element() scheme.
Currently, only XInclude 1.0 is supported, but with XML Inclusions (XInclude) 1.1 becoming stable, it would be interesting to see what would have to be added to the current implementation to turn it into an 1.1-compliant implementation.