BS ISO-IEC 2022-1994 pdf free download – Information technology — Character code structure and extension techniques.
6 Characters and character sets6.1 Types of characters and character sets
The structure of 8-bit and 7-bit codes specified by this International Standard makes use of the followingtypes of characters,character sets, and functions:
— fixed coded characters,
sets of coded graphic characters,
-sets of coded control functions (or control characters),-coded single additional control functions.
These components are specified respectively in 6.2 to 6.5 below.
The coded representations of the graphic characters and control functions are specified in relation tothe 8-bit and 7-bit code tables defined in 5.2 above. A coded representation for each type of component isspecified within columns 00 to 07 of the 8-bit and 7-bit code tables.For some components an alternativecoded representation is specified in columns 08 to 15 of the 8-bit code table, and is not applicable to
any 7-bit code.
6.2 Fixed coded characters6.2.1 Character DELETE
Name: DELETEAcronym: DEL
Coded representation: 07/15
DEL was originally used to erase or obliterate an erroneous or unwanted character in punched tape.DEL may be used for media -fill or time-fill. DEL characters may be inserted into, or removed from, aCC-data-element without affecting its information content, but such action may affect the informationlayout and/or the control of equipment.
6.2.2 Character ESCAPE
Name: ESCAPE
Acronym: ESC
Coded representation: 01/11
ESCAPE is a controlcharacter used for code extension purposes.It causes the meaning of a limited numberof the bit combinations following it in a CC-data-element to be changed. These bit combinations, togetherwith the preceding bit combination that represents the ESC character, constitute an escape sequence.Escape sequences provide the coded representations of code-identification functions and of some types ofcontrol functions. The various uses of escape sequences are specified in clause 13.Code identificationfunctions are specified in clauses 14 and 15.
6.2.3 Character SPACE
Name: SPACE
Acronym: SP
Coded representation: 02/00
SPACE is a graphic character. It has a visual representation consisting of the absence of a graphic symbol.It causes the active position to be advanced by one character position.
6.3 Sets of coded graphic characters
6.3.1 Types of coded graphic character set
A graphic character shall have a coded representation comprising one or more 8-bit combinations (bytes)in an 8-bit code, and one or more 7-bit combinations (bytes) in a 7-bit code. Within a coded graphic character set each character shall be represented by the same number of such bit combinations.
The bit combinations used to represent the graphic characters in a set shall be either from the six adjacentcolumns numbered 02 to 07 of the code tables or from the six adjacent columns numbered 10 to 15 ofthe 8-bit code table.
The type of a coded graphic character set is defined by the maximum number of graphice characters that theset can contain. The types of set specified here are illustrated in Figure 3.
A coded graphic character set in which each character is represented by a single bit combination shall be one of the following: .
– 94-character set, in positions 02/01 to 07/14, or 10/01 to 15/14;
(i.e. all positions in columns 02 to 07 except 02/00 and 07/15, or all positions in columns 10 to 15 except 10/00 and 15/15)
– 96-character set, in positions 02/00 to 07/15, or 10/00 to 15/15.
(i.e. all positions in columns 02 to 07, or in columns 10 to 15)
In a 94-character set no character shall be allocated to positions 02/00 and 07/15.
A coded graphic character set in which each character is represented by a sequence of n bit combinations,where n> 1, shall be one of the following: .
– 94n-character set,
– 96n-character set.BS ISO-IEC 2022 pdf download.