BLT = B = blue box
Blue Book n.
1. Informal name for one of the four standard references on the page-layout and graphics-control language PostScript ("PostScript Language Tutorial and Cookbook", Adobe Systems, Addison-Wesley 1985, QA76.73.P67P68, ISBN 0-201-10179-3); the other three official guides are known as the Green Book, the Red Book, and the White Book (sense 2). 2. Informal name for one of the three standard references on Smalltalk: "Smalltalk-80: The Language and its Implementation", David Robson, Addison-Wesley 1983, QA76.8.S635G64, ISBN 0-201-11371-63 (this book also has green and red siblings). 3. Any of the 1988 standards issued by the CCITT's ninth plenary assembly. These include, among other things, the X.400 email spec and the Group 1 through 4 fax standards. See also book titles.
--The Jargon File version 4.3.1, ed. ESR, this entry manually entered by rootbeer277.