ECMA 6-1991 7-Bit coded Character Set《7-位编码字符集 第6版》.pdf

1、Standard ECMA-66thEdition - December 1991Reprinted in electronic form in August 1997Standardizing Information and Communication SystemsPhone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http:/www.ecma.ch - Internet: helpdeskecma.ch7-Bit coded Character Set.Standard ECMA-66th Edition - December 1

2、991Standardizing Information and Communication SystemsPhone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http:/www.ecma.ch - Internet: helpdeskecma.chLL ECMA-006.DOC 28-01-99 10,387-Bit coded Character Set.Brief HistoryTechnical Committee TC1 of ECMA met for the first time in December 1960 to pr

3、epare standard codes for Input/Outputpurposes. On 30th April 1965, Standard ECMA-6 was adopted by the General Assembly of ECMA.Subsequent international activities necessitated three revisions of ECMA-6, which were issued in June 1967, July 1970 andAugust 1973. In the 3rd edition, TC1 introduced a ne

4、w concept, that of versions of the code and proposed at the same time anInternational Reference Version. This concept and this specific version were eventually adopted by ISO for the newInternational Standard ISO 646-1972 and by CCITT for the International Telegraph Alphabet No. 5 (CCITT Rec. V.3).I

5、n parallel to these developments, further work on extension of the 7-bit code was achieved. The techniques for extending therepertoire of the 7-bit code, remaining in a 7-bit environment, and for expanding it to 8-bit codes are described in StandardECMA-35 (ISO 2022). In application of these techniq

6、ues the structure of, and rules for, 8-bit codes are defined in StandardECMA-43 (ISO 4873).This 6th Edition corresponds to the 3rd edition of ISO 646 issued in 1991, a revision of the 1983 issue prepared by WG-7 ofISO/IEC/JTC1/SC2 in which several members of ECMA/TC1 were major contributors. The dif

7、ferences between the 5th andthe 6th editions are specified in annex C.Adopted by the General Assembly of ECMA in December 1991.- i -Table of contents1 Scope 12 Conformance and Implementation 12.1 Conformance 12.1.1 Conformance of information interchange 12.1.2 Conformance of devices 12.2 Implementat

8、ion 13 References 24 Definitions 24.1 Active position 24.2 Bit combination 24.3 Character 24.4 Character position 24.5 Coded character set; code 24.6 Coded-character-data-element (CC-data-element) 24.7 Code extension 24.8 Code table 24.9 Control character 34.10 Control function 34.11 Device 34.12 Es

9、cape sequence 34.13 Final byte 34.14 Graphic character 34.15 Graphic symbol 34.16 Repertoire 34.17 User 35 Notation, Code Table and Names 35.1 Notation 35.2 Code table 45.3 Names 46 Specification of the Coded Character Set 46.1 Structure 46.2 Control characters 56.3 Character SPACE 56.4 Graphic char

10、acters 56.4.1 Unique graphic character allocations 56.4.2 Alternative graphic character allocations 76.4.3 National or application-oriented graphic character allocations 86.5 Character DELETE 87 Composite Graphic Characters 88 Versions of the Coded Character Set 88.1 General 88.2 International Refer

11、ence Version (IRV) 98.3 National versions 9- ii -8.4 Application-oriented versions 109 Identification of Versions 109.1 Purpose and context of identification 109.2 Identification of a version 1010 Explanation of Code Tables No. 4 and No. 5 10Annex A - Specification of the C0 set 13Annex B - Guidelin

12、es for Standards derived from Standard ECMA-6 15Annex C - Differences between the 5thEdition (1983) and the present (6th) Edition of ECMA-6 171Scope1.1 This ECMA Standard specifies a set of 128 characters, (control characters and graphic characters such asletters, digits and symbols) with their code

13、d representation. Most of these characters are mandatory andunchangeable, but provision is made for some flexibility to accommodate national and other requirements.1.2 This ECMA Standard specifies a 7-bit coded character set with a number of options. It also providesguidance on how to exercise the o

14、ptions to define specific national versions and application-orientedversions. Furthermore it specifies the International Reference Version (IRV) in which such options have beenexercised.1.3 This character set is primarily intended for the interchange of information among data processing systemsand a

15、ssociated equipment, and within data communication systems. The need for graphic characters andcontrol functions in data processing has also been taken into account in determining this character set.1.4 This character set is applicable to alphabets of the Latin script.1.5 This character set allows t

16、he use of control characters for code extension where its character set isinsufficient for particular applications. Procedures for the use of these control characters are specified inStandard ECMA-35.1.6 The definitions of the control characters mentioned in this ECMA Standard are specified in Stand

17、ard ECMA-48. It is assumed that data associated with them are to be processed serially in a forward direction. Whenthey are included in strings of data which are processed other than serially in a forward direction or whenthey are included in data formatted for fixed-record processing they may have

18、undesirable effects or mayrequire additional special treatment to ensure that they result in their desired function.2 Conformance and Implementation2.1 Conformance2.1.1 Conformance of information interchangeA coded-character-data-element (CC-data-element) within coded information for interchange is

19、inconformance with this ECMA Standard if all the coded representations of characters within that CC-data-element conform to the requirements of 8.1.A claim of conformance shall identify the version adopted in accordance with 8.2 to 8.4.2.1.2 Conformance of devicesA device is in conformance with this

20、 ECMA Standard if it conforms to the requirements of 2.1.2.1, andeither or both of clauses 2.1.2.2 and 2.1.2.3 below. A claim of conformance shall identify the versionadopted.2.1.2.1 Device descriptionA device that conforms to this ECMA Standard shall be the subject of a description that identifies

21、themeans by which the user may supply characters to the device, or may recognize them when they aremade available to him, as specified respectively in clauses 2.1.2.2 and 2.1.2.3 below.2.1.2.2 Originating devicesAn originating device shall allow its user to supply any sequence of characters from the

22、 versionadopted, and shall be capable of transmitting their coded representations within a CC-data-element.2.1.2.3 Receiving devicesA receiving device shall be capable of receiving and interpreting any coded representations ofcharacters that are within a CC-data-element, and that conform to clause 2

23、.1.1 of this ECMA Standard,and shall make the corresponding characters available to its user in such a way that the user can identifythem from among those of the version adopted, and can distinguish them from each other.2.2 ImplementationThe use of this character set requires definitions of its impl

24、ementation in various media. For example, thesecould include punched tapes, punched cards, magnetic and optical interchangeable media and transmissionchannels, thus permitting interchange of data to take place either indirectly by means of an intermediate- 2 -recording on a physical medium, or by lo

25、cal connection of various units (such as input and output devicesand computers) or by means of data transmission equipment.The implementation of this coded character set in physical media and for transmission, taking into accountthe need for error checking, is the subject of other standards.3 Refere

26、ncesECMA-35: Code Extension Techniques, 4th EditionECMA-43: 8-Bit Coded Character Set - Structure and RulesECMA-48: Control Functions for Coded Character Sets, 5th EditionISO/IEC 10538: Control functions for text communication4 DefinitionsFor the purpose of this Standard the following definitions ap

27、ply.4.1 Active positionThe character position which is to image the graphic symbol representing the next graphic character orrelative to which the next control function is to be executed.NOTE 1In general, the active position is indicated in a display by a cursor.4.2 Bit combinationAn ordered set of

28、bits used for the representation of characters.4.3 CharacterA member of a set of elements used for the organization, control or representation of data.4.4 Character positionThe portion of a display that is imaging or is capable of imaging a graphic symbol.4.5 Coded character set; codeA set of unambi

29、guous rules that establishes a character set and the one-to-one relationship between thecharacters of the set and their bit combinations.4.6 Coded-character-data-element (CC-data-element)An element of interchanged information that is specified to consist of a sequence of coded representations ofchar

30、acters, in accordance with one or more identified standards for coded character sets.NOTE 2In a communication environment according to the Reference Model for Open Systems Interconnection ofISO 7498, a CC-data-element will form all or part of the information that corresponds to the Presentation-Prot

31、ocol-Data-Unit (PPDU) defined in that International Standard.NOTE 3When information interchange is accomplished by means of interchangeable media, a CC-data-element willform all or part of the information that corresponds to the user data, and not that recorded duringformatting and initialization.4.

32、7 Code extensionThe techniques for the encoding of characters that are not included in the character set of a given code.4.8 Code tableA table showing the character allocated to each bit combination in a code.- 3 -4.9 Control characterA control function the coded representation of which consists of

33、a single bit combination.4.10 Control functionAn action that affects the recording, processing, transmission, or interpretation of data, and that has a codedrepresentation consisting of one or more bit combinations.4.11 DeviceA component of information processing equipment which can transmit, and/or

34、 receive, coded informationwithin CC-data-elements.NOTE 4It may be an input/output device in the conventional sense, or a process such as an application program ora gateway function.4.12 Escape sequenceA string of bit combinations that is used for control purposes in code extension procedures. The f

35、irst of thesebit combinations represents the control function ESCAPE.4.13 Final byteThe bit combination that terminates an escape sequence or a control sequence.4.14 Graphic characterA character, other than a control function, that has a visual representation normally hand-written, printed ordisplay

36、ed, and that has a coded representation consisting of one or more bit combinations.4.15 Graphic symbolA visual representation of a graphic character or of a control function.4.16 RepertoireA specified set of characters that are represented by means of one or more bit combinations of a codedcharacter

37、 set.4.17 UserA person or other entity that invokes the services provided by a device.NOTE 5This entity may be a process such as an application program if the “device“ is a code converter or agateway function, for example.NOTE 6The characters, as supplied by the user or made available to him, may be

38、 in the form of codes local to thedevice, or of non-conventional visible representations, provided that clause 2.1.2 above is satisfied.5 Notation, Code Table and Names5.1 NotationThe bits of the bit combinations of the 7-bit code are identified by b7, b6, b5, b4, b3, b2 and b1, where b7 isthe highe

39、st-order, or most-significant, bit and b1 is the lowest-order, or least-significant, bit.The bit combinations may be interpreted to represent integers in the range 0 to 127 in binary notation byattributing the following weights to the individual bits:Bit : b7b6b5b4b3b2b1Weight : 64 32 16 8 4 2 1- 4

40、-In this ECMA Standard, the bit combinations are identified by notations of the form x/y, where x is a numberin the range 0 to 7 and y is a number in the range 0 to 15. The correspondence between the notations of theform x/y and the bit combinations consisting of the bits b7 to b1 is as follows:- x

41、is the number represented by b7, b6 and b5 where these bits are given the weights 4, 2 and 1respectively;- y is the number represented by b4, b3, b2 and b1 where these bits are given the weights 8, 4, 2 and 1respectively.The notations of the form x/y are the same as those used to identify code table

42、 positions, where x is thecolumn number and y the row number (see clause 5.2).5.2 Code tableA 7-bit code table consists of 128 positions arranged in 8 columns and 16 rows. The columns are numbered 0to 7 and the rows 0 to 15.The code table positions are identified by notations of the form x/y, where

43、x is the column number and y isthe row number.The positions of the code table are in one-to-one correspondence with the bit combinations of the code. Thenotation of a code table position, of the form x/y, is the same as that of the corresponding bit combination.5.3 NamesThis ECMA Standard assigns a

44、unique name to each character. In addition, it specifies an acronym for eachcontrol character and for the characters SPACE and DELETE, and a graphic symbol for each graphiccharacter. By convention, only capital letters, space and hyphen are used for writing the names of thecharacters. For acronyms o

45、nly capital letters and digits are used. It is intended that the acronyms and thisconvention be retained in all translations of the text.The names chosen to denote graphic characters are intended to reflect their customary meaning. However,this ECMA Standard does not define and does not restrict the

46、 meanings of graphic characters. Neither does itspecify a particular style or font design for the graphic characters when imaged.6 Specification of the Coded Character Set6.1 StructureThe coded character set of this ECMA Standard shall have the following structure.- a C0 control character set of up

47、to 32 control characters;- the graphic character SPACE (SP);- a G0 graphic character set of up to 94 graphic characters;- the character DELETE (DEL).- 5 -97-0171G0C0SPDELFigure 1 - Structure of the 7-bit coded character set6.2 Control charactersThe control characters of the C0 set shall be represent

48、ed by bit combinations as specified in annex A.6.3 Character SPACEThe acronym of the character SPACE is SP and it is represented by bit combination 2/0.This character is a graphic character, it has a visual representation consisting of the absence of a graphicsymbol.6.4 Graphic charactersThe 94 bit

49、combinations 2/1 to 7/14 are used for the representation of graphic characters as specified in6.4.1, 6.4.2 and 6.4.3.All graphic characters shall be spacing characters, that is, they cause the active position to advance by onecharacter position.6.4.1 Unique graphic character allocationsA unique graphic character is allocated to each of the 82 bit combinations 2/1, 2/2, 2/5 to 3/15, 4/1 to5/10, 5/15 and 6/1 to 7/10. These graphic characters are specified in table 1.- 6 -Table 1 - Unique graphic character allocationsGraphicSymbolName Codedrepresentation! EXCLAMATION MARK 2/1“ QUOTATION MA