This seems like an encyclopedia for GIS. How does this Body of Knowledge differ from other encyclopedias that have been published in the past?

The purpose of the GIS&T BoK is not to replace any of the comprehensive reference books that have been published in the past;  there are roles for many reference collections. By having the GIS&T Body of Knowledge exist now only in digital form, UCGIS is able to ensure that the content can be updated on a more regular basis and be kept as current and thorough as possible. A digital format also allows for services such as text-based analysis. Open and online access will always allow a greater reach and extent than traditional book formats, and will enable multi-media content as well.