The Secure World Foundation and the Space Policy Institute (SPI) of George Washington University have released a joint publication entitled "A Guide to Space Law Terms". Edited by Professor Henry Hertzfeld, the publication is the first to define more than 80 space law terms and phrases. The document is intended to be an authoritative and comprehensive guide to space law terminology, with room for growth and change as readers submit revisions and commentary. It outlines seven categories of definitions so that the reader can understand usage in different situations. For example, a variety of approaches to definitions are provided for space law terms and phrases such as international liability, space object or space flight participants.