:cd tilde: /C-D til-d*/ /vi./ To go home. From the Unix C-shell and Korn-shell command `cd ~', which takes one to one's `$HOME' (`cd' with no arguments happens to do the same thing). By extension, may be used with other arguments; thus, over an electronic chat link, `cd ~coffee' would mean "I'm going to the coffee machine."
:CDA: /C-D-A/ The "Communications Decency Act" of 1996, passed on {Black Thursday} as section 502 of a major telecommunications reform bill. The CDA made it a federal crime in the USA to send a communication which is "obscene, lewd, lascivious, filthy, or indecent, with intent to annoy, abuse, threaten, or harass another person." It also threatens with imprisonment anyone who "knowingly" makes accessible to minors any message that "describes, in terms patently offensive as measured by contemporary community standards, sexual or excretory activities or organs".
While the CDA was sold as a measure to protect minors from the putative evils of pornography, the repressive political aims of the bill were laid bare by the Hyde amendment, which intended to outlaw discussion of abortion on the Internet.
To say that this direct attack on First Amendment free-speech rights was not well received on the Internet would be putting it mildly. A firestorm of protest followed, including a February 29th mass demonstration by thousands of netters who turned their {home page}s black for 48 hours. Several civil-rights groups and computing/telecommunications companies sought an immediate injunction to block enforcement of the CDA pending a constitutional challenge. This injunction was granted on the likelihood that plaintiffs would prevail on the merits of the case. At time of writing (Spring 1996), the fate of the CDA, and its effect on the Internet, is still unknown. See also {Exon}.
To join the fight against the CDA (if it's still law) and other forms of Internet censorship, visit the Center for Democracy and Technology Home Page at http://www.cdt.org.
:cdr: /ku'dr/ or /kuh'dr/ /vt./ [from LISP] To skip past the first item from a list of things (generalized from the LISP operation on binary tree structures, which returns a list consisting of all but the first element of its argument). In the form `cdr down', to trace down a list of elements: "Shall we cdr down the agenda?" Usage: silly. See also {loop through}.
Historical note: The instruction format of the IBM 704 that hosted the original LISP implementation featured two 15-bit fields called the `address' and `decrement' parts. The term `cdr' was originally `Contents of Decrement part of Register'. Similarly, `car' stood for `Contents of Address part of Register'.
The cdr and car operations have since become bases for formation of compound metaphors in non-LISP contexts. GLS recalls, for example, a programming project in which strings were represented as linked lists; the get-character and skip-character operations were of course called CHAR and CHDR.
:chad: /chad/ /n./ 1. The perforated edge strips on printer paper, after they have been separated from the printed portion. Also called {selvage} and {perf}. 2. obs. The confetti-like paper bits punched out of cards or paper tape; this has also been called `chaff', `computer confetti', and `keypunch droppings'. This use may now be mainstream; it has been reported seen (1993) in directions for a card-based voting machine in California.
Historical note: One correspondent believes `chad' (sense 2) derives from the Chadless keypunch (named for its inventor), which cut little u-shaped tabs in the card to make a hole when the tab folded back, rather than punching out a circle/rectangle; it was clear that if the Chadless keypunch didn't make them, then the stuff that other keypunches made had to be `chad'. There is a legend that the word was originally acronymic, standing for "Card Hole Aggregate Debris", but this has all the earmarks of a bogus folk etymology.