PARSE
[from linguistic terminology]
v. 1. To determine the syntactic structure of a sentence or other utterance (close to the standard English meaning). Example: "That was the one I saw you." "I can't parse that."
2. More generally, to understand or comprehend. "It's very simple; you just kretch the glims and then aos the zotz." "I can't parse that."
3. Of fish, to have to remove the bones yourself (usually at a Chinese restaurant). "I object to parsing fish" means "I don't want to get a whole fish, but a sliced one is okay." A "parsed fish" has been deboned. There is some controversy over whether "unparsed" should mean "bony", or also mean "deboned".

PATCH
1. n. A temporary addition to a piece of code, usually as a quick-and-dirty remedy to an existing bug or misfeature. A patch may or may not work, and may or may not eventually be incorporated permanently into the program.
2. v. To insert a patch into a piece of code.

PDL (piddle or puddle)
[acronym for Push Down List]
n. 1. A LIFO queue (stack); more loosely, any priority queue; even more loosely, any queue. A person's pdl is the set of things he has to do in the future. One speaks of the next project to be attacked as having risen to the top of the pdl. "I'm afraid I've got real work to do, so this'll have to be pushed way down on my pdl." See PUSH and POP.
2. Dave Lebling (PDL@DM)

PESSIMAL
[Latin-based antonym for "optimal"]
adj. Maximally bad. "This is a pessimal situation."

PESSIMIZING COMPILER
n. A compiler that produces object code that is worse than the straightforward or obvious translation

PHANTOM
n. (Stanford) The SAIL equivalent of a DRAGON (q.v.). Typical phantoms include the accounting program, the news-wire monitor, and the lpt and xgp spoolers.

PHASE (of people)
1. n. The phase of one's waking-sleeping schedule with respect to the standard 24-hour cycle. This is a useful concept among people who often work at night according to no fixed schedule. It is not uncommon to change one's phase by as much as six hours/day on a regular basis. "What's your phase?" "I've been getting in about 8 PM lately, but I'm going to work around to the day schedule by Friday." A person who is roughly 12 hours out of phase is sometimes said to be in "night mode". (The term "day mode" is also used, but less frequently.)
2. CHANGE PHASE THE HARD WAY: To stay awake for a very long time in order to get into a different phase.
3. CHANGE PHASE THE EASY WAY: To stay asleep etc.

PHASE OF THE MOON
n. Used humorously as a random parameter on which something is said to depend. Sometimes implies unreliability of whatever is dependent, or that reliability seems to be dependent on conditions nobody has been able to determine. "This feature depends on having the channel open in mumble mode, having the foo switch set, and on the phase of the moon."

PLUGH
[from the Adventure game]
v. See XYZZY.

POM
n. Phase of the moon (q.v.). Usage: usually used in the phrase "POM dependent" which means flakey (q.v.).

POP
[based on the stack operation that removes the top of a stack, and the fact that procedure return addresses are saved on the stack]
dialect: POPJ (pop-jay), based on the PDP-10 procedure return instruction.
v. To return from a digression. By verb doubling, "Popj, popj" means roughly, "Now let's see, where were we?"

PPN (pip'in)
[DEC terminology, short for Project-Programmer Number]
n. 1. A combination `project' (directory name) and programmer name, used to identify a specific directory belonging to that user. For instance, "FOO,BAR" would be the FOO directory for user BAR. Since the name is restricted to three letters, the programmer name is usually the person's initials, though sometimes it is a nickname or other special sequence. (Standard DEC setup is to have two octal numbers instead of characters; hence the original acronym.)
2. Often used loosely to refer to the programmer name alone. "I want to send you some mail; what's your ppn?" Usage: not used at MIT, since ITS does not use ppn's. The equivalent terms would be UNAME and SNAME, depending on context, but these are not used except in their technical senses.

PROTOCOL
See DO PROTOCOL

PSEUDOPRIME
n. A backgammon prime (six consecutive occupied points) with one point missing.

PTY (pity)
n. Pseudo TTY, a simulated TTY used to run a job under the supervision of another job.
PTYJOB (pity-job) n. The job being run on the PTY. Also a common general-purpose program for creating and using PTYs. This is DEC and SAIL terminology; the MIT equivalent is STY.

PUNT
[from the punch line of an old joke: "Drop back 15 yards and punt"] v. To give up, typically without any intention of retrying

PUSH
[based on the stack operation that puts the current information on a stack, and the fact that procedure call addresses are saved on the stack]
dialect: PUSHJ (push-jay), based on the PDP-10 procedure call instruction.
v. To enter upon a digression, to save the current discussion for later.