1. Xdelta (X for XCF: the eXperimental Computing Facility at Berkeley) is a binary delta generator (like a diff program for binaries) and an RCS version control replacement library. The Xdelta library performs its work independently of the actual format used to encode the file and is intended to be used by various higher-level programs such as XCF's Project Revision Control System (PRCS). PRCS is a front end for aversion control toolset. Xdelta uses a binary file delta algorithm toreplace the standard diff program used by RCS. From Redhat 8.0 RPM