The 1944 Bletchley Park Cryptographic Dictionary

- 45 -

IDENTIFICATION :

(in book-breaking, etc.). A solved or 'recovered' meaning for a code-group.

IDLE :

Having no necessary or significant function.

ILLEGAL :

Not in conformity with established practice.

INDEX :

(especially). To index by cipher groups; also, to record occurrences of (code-groups) as a process in book-breaking.

INDICATIVE :

(in Met.). A three figure number indicating the Meteorological Station concerned, and forming the first three figures of a synoptic report.
(It may be either a Principal Indicative, i.e. one of 1000 three-figure groups assigned to 1000 different Met. Stations in Europe by International agreement; or a subsidiary or Nationa1 Indicative, i.e. a group, additional to the original 1000, assigned nationally to a station not on the original list).

INDICATOR :

One or more letter or figure or letter-and-figure groups (either sent in clear or enciphered on a separate system and placed at the beginning and/or end of a message, or in the body of it) indicating the key or subtractor used or, in the case of a long subtractor, the starting- point or starting-point and finishing-point.

INDICATOR GROUP :

A group forming the whole or part of an indicator, whether enciphered or not.

INDICATOR SYSTEM :

System by which key or starting-point indicators are enciphered or concealed.

INTERNAL :

1. (of repeats). Occurring within the same message.

2. Occurring in or derived from one particular type of traffic and applied to that traffic.

| previous page | next page | index page |