ANSI INCITS ISO IEC TR 15285-1988 Information technology - An operational model for characters and glyphs (Technical Report).pdf

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1、 INCITS/ISO/IEC TR 15285:1988 2015 (ISO/IEC TR 15285:1998, IDT) Information technology - An operational model for characters and glyphs (Technical Report) INCITS/ISO/IEC TR 15285:1988 2015 PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this f

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5、 Date of Registration: 2/1/2015 Published by American National Standards Institute, 25 West 43rd Street, New York, New York 10036 Copyright 2015 by Information Technology Industry Council (ITI). All rights reserved. These materials are subject to copyright claims of International Standardization Org

6、anization (ISO), International Electrotechnical Commission (IEC), American National Standards Institute (ANSI), and Information Technology Industry Council (ITI). Not for resale. No part of this publication may be reproduced in any form, including an electronic retrieval system, without the prior wr

7、itten permission of ITI. All requests pertaining to this standard should be submitted to ITI, 1101 K Street NW, Suite 610, Washington DC 20005. Printed in the United States of America ii ITIC 2015 All rights reserved TECHNICAL REPORT ISOAEC TR 15285 First edition 1998-12-15 Information technology -

8、An operational model for characters and glyphs Technologies de Iinforma tion - Mod - Type 2, when the subject is still under technical development or where for any other reason there is the future but not immediate possibility of an agreement on an International Standard; - Type 3, when a technical

9、committee has collected data of a dif- ferent kind from that which is normally published as an Interna- tional Standard (“state of the art”, for example). Technical Reports of types 1 and 2 are subject to review within three years of publication to decide whether they can be transformed into Interna

10、tional Standards. Technical Reports of type 3 do not neces- sarily have to be reviewed until the data they provide are considered to be no longer valid or useful. ISOAEC TR 15285, which is a Technical Report of type 3, was pre- pared by Joint Technical Committee ISOAEC JTC 1, information technology,

11、 Subcommittee SC 2, Coded character sets, and Sub- committee SC 18, Document processing and related communication (which has since been reorganized into SC 34, Document description and processing languages). lSO/lEC 15067-2: 1997(E) 0 ISOAEC Introduction The Home Electronic System is a standard unde

12、r development by Working Group 1 (WGI) of Subcommittee 25 (SC25), interconnection of information Technology Equipment, under Joint Technical Committee 1 (JTCl) of the IS0 and IEC. The physical elements constituting lighting control systems are listed. The physical connection of these elements on a h

13、ome control system medium is shown. Then, a generic logical model is presented. The relationship of this model to typical systems of varying complexity is discussed. TECHNICAL REPORT 0 ISO/IEC ISO/IEC TR 15285:1998 (El Information technology - An operational model for characters and glyphs 1 Scope T

14、he purpose of this Technical Report is to provide a general framework for discussing characters and glyphs. The framework is applicable to a variety of coded character sets and glyph-identification schemes. For illustration, this Technical Report uses ex- amples from characters coded in ISO/IEC 1064

15、6 and glyphs registered according to ISO/IEC 10036. This Technical Report - differentiates between coded charac- ters and registered glyphs - identifies the domain of use of coded characters and glyph identifiers - provides a conceptual framework for the formatting and presentation of coded characte

16、r data using glyph iden- tifiers and glyph representations This Technical Report describes idealized principles that were not completely followed in coding characters for ISO/IEC 10646 and in registering glyphs according to lSO/IEC 10036. The fact that ISO/IEC 10646, ISO/IEC 10036, and other standar

17、ds do not completely follow the principles in the model does not invalidate the model and does not diminish the utility of having the model. 2 References ISO/IEC 9541-l : 1991, information technol- ogy - Font information interchange - Part 1: Architecture. ISO/IEC 10036: 1996, information technol- o

18、gy - Font information interchange - Pro- cedures for registration of font-related iden- tifiers. ISO/IEC 10180: 1995, information technol- ogy - Processing languages - Standard Page Description Language (SPDL). ISO/IEC 10646-l : 1993, information tech- nology - Universal Multiple-Octet Coded Charact

19、er Set (KS) - Part 1: Architecture and Basic Multilingual Plane. 3 Definitions For the purpose of this Technical Report, the following definitions apply. The defini- tions have been extracted from the ISO/IEC 9541-l: 1991 and ISO/IEC 10646-l: 1993 standards. 3.1 character: A member of a set of ele-

20、ments used for the organisation, control, or representation of data. (ISO/I EC 10646-l : 1993) 3.2 coded character set: A set of unam- biguous rules that establishes a character set and the relationship between the char- acters of the set and their coded represen- tation. (ISO/IEC 10646-l: 1993) 3.3

21、 font: A collection of glyph images having the same basic design, e.g. Courier Bold Oblique. (lSO/lEC 9541-l: 1991) 3.4 font resource: A collection of glyph representations together with descriptive and font metric information which are rele- vant to the collection of glyph representa- tions as a wh

22、ole. (ISO/IEC 9541-l : 1991) 3.5 glyph: A recognizable abstract graphic symbol which is independent of any specific design. (ISO/IEC 9541-l : 1991) 3.6 glyph collection: An identified set of glyphs. (ISO/IEC 9541-i: 1991) 3.7 glyph image: An image of a glyph, as obtained from a glyph representation

23、dis- played on a presentation surface. (ISOIIEC 9541-l : 1991) See the definition of graphic symbol. 3.8 glyph metrics: The set of information in a glyph representation used for defining 1 lSO/lEC TR 15285: 1998 (E) 0 ISOAEC the dimensions and positioning of the glyph shape. (ISO/IEC 9541-1: 1991) 3

24、.9 glyph representation: The glyph shape and glyph metrics associated with a specific glyph in a font resource. (ISO/IEC 9541-l : 1991) 3.10 glyph shape: The set of information in a glyph representation used for defining the shape which represents the glyph. (ISO/iEC 9541-I : 1991) 3.11 graphic char

25、acter: A character, other than a control function, that has a visual representation normally handwritten, printed, or displayed. (ISO/IEC 10646-I : 1993) 3.12 graphic symbol: The visual repre- sentation of a graphic character or of a composite sequence. (ISO/IEC 10646-l : 1993) See the definition of

26、 glyph image. 3.13 presentation of a graphic symbol: The process of writing, printing, or display- ing a graphic symbol. (ISO/IEC 10646-I : 1993) 3.14 presentation form: In the presenta- tion of some scripts, a form of a graphic symbol representing a character that de- pends on the position of the c

27、haracter rela- tive to other characters. (ISO/IEC 10646-I: 1993) 3.15 presentation surface: A virtual rep- resentation of a presentation medium (page, graphic display, etc.) maintained by the presentation process, on which all glyph shapes are to be imaged. (ISO/IEC 9541-1: 1991) 3.16 repertoire: A

28、specified set of charac- ters that are represented in a coded char- acter set. (ISO/IEC 10646-I : 1993) 4 Character and glyph distinctions The character and glyph definitions in clause 3, which were taken from ISO/IEC 10646 and ISO/IEC 9541, were developed independently and contain terminology that

29、requires explanation. In information technology, characters are abstract information elements in the domain of coding for data representation and, in particular, data interchange. Coded char- acter set standards assign numeric values, character names, and representative (sam- ple) images to each cha

30、racter contained in a coded character set. Typically a character is given a name, which also serves to dif- ferentiate it from the other characters of the coded character set. The precise semantics and appearance of the information elements in any given implementation are not defined by those standa

31、rds for coded character sets. This apparent lack of definition is not considered to be a defect in the standards. Recognizing that the information may be acted upon (deciphered, sorted, trans- formed, formatted, archived, presented, etc.) by many different application proc- esses during its lifetime

32、, standards for coded character sets are defined as a basis for information interchange. In information technology, glyphs are ab- stract presentation elements in the domain of presentation processing. The ISO/IEC 10036 standard for glyph registration de- fines the process for assigning glyph identi

33、- fiers, glyph descriptions, and representative (sample) images to each glyph submitted for registration. The precise usage and ap- pearance of these presentation elements in any implemented font resource is not de- fined by those glyph registration activities. As with the coded character set standa

34、rds, this apparent lack of definition is not con- sidered to be a defect in the standards. Glyph identifiers are unambiguously as- signed as a basis for tagging presentation elements in and among interchanged font resources, recognizing that the font-specific design information may vary from one fon

35、t resource to another. Characters and glyphs are closely related, with many attributes in common and yet with distinctions that make it essential that they be managed in information processing as separate entities. The ISO/IEC 10646 standard recognizes the distinction between 2 0 ISO/IEC ISOAEC TR 1

36、5285: 1998 (E) characters and their visual representation by defining the term, graphic symbol. The graphic symbol of SC 2 standards and the glyph image of SC 18 standards represent equivalent concepts. However, glyph and its associated ISO/IEC 9541 terminology are preferred when referring to presen

37、tation and presentation processing. The historical association of characters and glyphs has resulted in character sets main- taining distinctions that cannot be founded on distinctions in meaning, but only on dis- tinctions in shape. Similarly, the glyph reg- istration authority and the SC 18 font r

38、e- source model have made use of criteria based on meaning to abstract potential dis- tinctions in shape. In practice, ISO/IEC 10646 contains characters that appear to be instances of glyphs, while the glyph registry prescribed by ISO/IEC 10036 contains glyphs that appear to be designated as ab- str

39、act characters. In both cases, the ideal nature of characters and glyphs has been compromised to a degree. For example, in ISO/IEC 10646-1, SC 2 coded the Yi” glyph into the character U+FBOl LATIN SMALL LIGATURE FI 77” for round-trip integrity with other standards.) (See Annex 8.5 The “round-trip ru

40、le”.) Also, the JTC 1 Registra- tion Authority (AFII) for ISO/IEC 10036 could have registered the same glyph iden- tifier for the “A” glyph and used it for the U+OO41 LATIN CAPITAL LEITER A “A” charac- ter, for the U+O391 GREEK CAPITAL LETTER ALPHA “A” character, and the U+O410 CYRILLIC CAPITAL LETT

41、ER A “A” character. However, AFII instead registered three glyph identifiers. Within the realm of information technology, an ideal characterization of characters and glyphs and their relationship may be stated as follows: - A character conveys distinctions in meaning or sounds. A character has no in

42、trinsic appearance. 1) This Technical Report describes a character in terms of its 10646 code position (U+FBOl), its 10646 name (LATIN SMALL LIGATURE FI), and illus- trates it with a representative glyph in quotation marks (“fi”). - A glyph conveys distinctions in form or appearance. A glyph has no

43、intrinsic meaning. - One or more characters may be de- picted by no, one, or multiple glyph rep- resentations (instances of an abstract glyph) in a way that may depend on the context. 5 Operational model 5.1 Character and glyph domains Character information has two primary do- mains as illustrated i

44、n Figure 1 on the next page. The first pertains to the processing of the content, that is, the meaning or phonetic value of the character information. This is depicted on the left side of the figure. The second pertains to the presentation of the content of the character information. This is depicte

45、d on the right side of the figure.21 Each domain places different requirements on the representation of the character in- formation. For example, searching for char- acter information in a database and sorting records containing character information entail different requirements from those found in

46、 presenting characters on paper. The former processes are primarily con- cerned with the content of data and have little or no concern about the appearance that the data may take. On the other hand, a composition and lay- out process has little concern for the con- tent of data, but great concern ab

47、out its appearance. In general, processing of char- acter information in the content domain is independent of font resources, whereas processing in the presentation domain is strongly dependent on the font resource used for the presentation of the character information. However, processes that per-

48、form transformations from one domain to the other are aware of both the content and appearance of characters. For example, a character recognition process converts im- 2) ISO/IEC 6429 also depicts a e-layer structure. For ISO/IEC 6429, the data layer could use charac- ters, and the presentation laye

49、r could use glyphs to present the characters in the data layer. ISOAEC TR 15285: 1998 (E) 0 ISOAEC Characters Content Processing Operations: Data Entry Search Sort/Order Spell Checking Grammar Checking Layout Glyph Selection and Substitution D Operations between Domains I Character Recognition Mouse Selection Glyphs Appearance Processing Operations: Format Display Print Figure 1 - Character and glyph domains ages into coded characters. Also, a para- graph-level hyphenation process is an ex-