logical

(From the technical term "logical device", wherein a physical

device is referred to by an arbitrary "logical" name) Having

the role of. If a person (say, Les Earnest at SAIL) who had

long held a certain post left and were replaced, the

replacement would for a while be known as the "logical" Les

Earnest. (This does not imply any judgment on the

replacement).

Compare virtual.

At Stanford, "logical" compass directions denote a coordinate

system in which "logical north" is toward San Francisco,

"logical west" is toward the ocean, etc., even though logical

north varies between physical (true) north near San Francisco

and physical west near San Jose. (The best rule of thumb here

is that, by definition, El Camino Real always runs logical

north-and-south.) In giving directions, one might say: "To

get to Rincon Tarasco restaurant, get onto El Camino Bignum

going logical north." Using the word "logical" helps to

prevent the recipient from worrying about that the fact that

the sun is setting almost directly in front of him. The

concept is reinforced by North American highways which are

almost, but not quite, consistently labelled with logical

rather than physical directions.

A similar situation exists at MIT: Route 128 (famous for the

electronics industry that has grown up along it) is a

3-quarters circle surrounding Boston at a radius of 10 miles,

terminating near the coastline at each end. It would be most

precise to describe the two directions along this highway as

"clockwise" and "counterclockwise", but the road signs all say

"north" and "south", respectively. A hacker might describe

these directions as "logical north" and "logical south", to

indicate that they are conventional directions not

corresponding to the usual denotation for those words. (If

you went logical south along the entire length of route 128,

you would start out going northwest, curve around to the

south, and finish headed due east, passing along one infamous

stretch of pavement that is simultaneously route 128 south and

Interstate 93 north, and is signed as such!)

[Jargon File]

(1995-01-24)