of {bitblt}. It referred to any large bit-field copy or move
operation (one resource-intensive memory-shuffling operation done
on pre-paged versions of ITS, WAITS, and TOPS-10 was sardonically
referred to as `The Big BLT'). The jargon usage has outlasted the
{PDP-10} BLock Transfer instruction from which {BLT} derives;
nowadays, the assembler mnemonic {BLT} almost always means
`Branch if Less Than zero'.

:Blue Book: n. 1. Informal name for one of the three 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 two 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 is also associated with green and red
books). 3. Any of the 1988 standards issued by the CCITT's
ninth plenary assembly. Until now, they have changed color each
review cycle (1984 was {Red Book}, 1992 would be {Green
Book}); however, it is rumored that this convention is going to be
dropped before 1992. These include, among other things, the
X.400 email spec and the Group 1 through 4 fax standards. See also
{{book titles}}.

:Blue Glue: [IBM] n. IBM's SNA (Systems Network Architecture), an
incredibly {losing} and {bletcherous} communications protocol
widely favored at commercial shops that don't know any better. The
official IBM definition is "that which binds blue boxes