:Open DeathTrap: n. Abusive hackerism for the Santa Cruz Operation's `Open DeskTop' product, a Motif-based graphical interface over their UNIX. The funniest part is that this was coined by SCO's own developers…compare {AIDX}, {terminak}, {Macintrash} {Nominal Semidestructor}, {ScumOS}, {sun-stools}, {HP-SUX}.
:open switch: [IBM: prob. from railroading] n. An unresolved question, issue, or problem.
:operating system:: [techspeak] n. (Often abbreviated `OS') The foundation software of a machine, of course; that which schedules tasks, allocates storage, and presents a default interface to the user between applications. The facilities an operating system provides and its general design philosophy exert an extremely strong influence on programming style and on the technical cultures that grow up around its host machines. Hacker folklore has been shaped primarily by the {{UNIX}}, {{ITS}}, {{TOPS-10}}, {{TOPS-20}}/{{TWENEX}}, {{WAITS}}, {{CP/M}}, {{MS-DOS}}, and {{Multics}} operating systems (most importantly by ITS and UNIX).
:optical diff: n. See {vdiff}.
:optical grep: n. See {vgrep}.
:Orange Book: n. The U.S. Government's standards document `Trusted Computer System Evaluation Criteria, DOD standard 5200.28-STD, December, 1985' which characterize secure computing architectures and defines levels A1 (most secure) through D (least). Stock UNIXes are roughly C1, and can be upgraded to about C2 without excessive pain. See also {{book titles}}.
:oriental food:: n. Hackers display an intense tropism towards oriental cuisine, especially Chinese, and especially of the spicier varieties such as Szechuan and Hunan. This phenomenon (which has also been observed in subcultures that overlap heavily with hackerdom, most notably science-fiction fandom) has never been satisfactorily explained, but is sufficiently intense that one can assume the target of a hackish dinner expedition to be the best local Chinese place and be right at least three times out of four. See also {ravs}, {great-wall}, {stir-fried random}, {laser chicken}, {Yu-Shiang Whole Fish}. Thai, Indian, Korean, and Vietnamese cuisines are also quite popular.
:orphan: [UNIX] n. A process whose parent has died; one inherited by `init(1)'. Compare {zombie}.
:orphaned i-node: /or'f*nd i:'nohd/ [UNIX] n. 1. [techspeak] A file that retains storage but no longer appears in the directories of a filesystem. 2. By extension, a pejorative for any person serving no useful function within some organization, esp. {lion food} without subordinates.
:orthogonal: [from mathematics] adj. Mutually independent; well separated; sometimes, irrelevant to. Used in a generalization of its mathematical meaning to describe sets of primitives or capabilities that, like a vector basis in geometry, span the entire `capability space' of the system and are in some sense non-overlapping or mutually independent. For example, in architectures such as the PDP-11 or VAX where all or nearly all registers can be used interchangeably in any role with respect to any instruction, the register set is said to be orthogonal. Or, in logic, the set of operators `not' and `or' is orthogonal, but the set `nand', `or', and `not' is not (because any one of these can be expressed in terms of the others). Also used in comments on human discourse: "This may be orthogonal to the discussion, but…."