Green Book n. 1. One of the three standard PostScript references: "PostScript Language Program Design", bylined `Adobe Systems' (Addison-Wesley, 1988; QA76.73.P67P66 ISBN 0-201-14396-8); see also Red Book, Blue Book, and the White Book (sense 2). 2. Informal name for one of the three standard references on SmallTalk: "Smalltalk-80: Bits of History, Words of Advice", by Glenn Krasner (Addison-Wesley, 1983; QA76.8.S635S58; ISBN 0-201-11669-3) (this, too, is associated with blue and red books). 3. The "X/Open Compatibility Guide", which defines an international standard UNIX environment that is a proper superset of POSIX/SVID; also includes descriptions of a standard utility toolkit, systems administrations features, and the like. This grimoire is taken with particular seriousness in Europe. See Purple Book. 4. The IEEE 1003.1 POSIX Operating Systems Interface standard has been dubbed "The Ugly Green Book". 5. Any of the 1992 standards issued by the CCITT's tenth plenary assembly. These include, among other things, the X.400 email standard and the Group 1 through 4 fax standards. See also book titles.