:alt: /awlt/ 1. /n./ The alt shift key on an IBM PC or
{clone} keyboard; see {bucky bits}, sense 2 (though typical
PC usage does not simply set the 0200 bit). 2. /n./ The `clover'
or `Command' key on a Macintosh; use of this term usually reveals
that the speaker hacked PCs before coming to the Mac (see also
{feature key}). Some Mac hackers, confusingly, reserve `alt'
for the Option key (and it is so labeled on some Mac II keyboards).
3. /n.,obs/. [PDP-10; often capitalized to ALT] Alternate name for
the ASCII ESC character (ASCII 0011011), after the keycap labeling
on some older terminals; also `altmode' (/awlt'mohd/). This
character was almost never pronounced `escape' on an ITS system,
in {TECO}, or under TOPS-10 -- always alt, as in "Type alt alt
to end a TECO command" or "alt-U onto the system" (for "log
onto the [ITS] system"). This usage probably arose because alt is
more convenient to say than `escape', especially when followed by
another alt or a character (or another alt *and* a character,
for that matter). 4. The alt hierarchy on Usenet, the tree of
newsgroups created by users without a formal vote and approval
procedure. There is a myth, not entirely implausible, that
alt is acronymic for "anarchists, lunatics, and terrorists";
but in fact it is simply short for "alternative".

:alt bit: /awlt bit/ [from alternate] /adj./ See {meta
bit}.

:altmode: /n./ Syn. {alt} sense 3.

:Aluminum Book: /n./ [MIT] "Common LISP: The Language", by
Guy L. Steele Jr. (Digital Press, first edition 1984, second