1、INTERNATIONAL STANDARD lSO/IEC 9592-3 Second edition 1997-11-15 Information technology - Computer graphics and image processing - Programmers Hierarchical Interactive Graphics System (PHIGS) - Part 3: Specification for clear-text encoding of archive file Technologies de /information - lnfographie et
2、 traitement de /image - Interface de programmation du systkme graphique hkrarchisk (PHIGS) - Pat-tie 3: Spkcification du codage mode texte en clair du fichier darchive Reference number ISOAEC 9592-3: 1997(E) Adopted by INCITS (InterNational Committee for Information Technology Standards) as an Ameri
3、can National Standard.Date of ANSI Approval: 1/12/99Published by American National Standards Institute,25 West 43rd Street, New York, New York 10036Copyright 2002 by Information Technology Industry Council (ITI).All rights reserved.These materials are subject to copyright claims of International Sta
4、ndardization Organization (ISO), InternationalElectrotechnical 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, withou
5、tthe prior written permission of ITI. All requests pertaining to this standard should be submitted to ITI, 1250 Eye Street NW,Washington, DC 20005.Printed in the United States of AmericaISWIEC 9592-3:1997(E) Contents 1 Scope . .l 2 Normative references . 3 Definitions . .3 4 Clear text encoding form
6、at .4 4.1 Notational conventions . .4 4.2 Archive file format . 4 4.2.1 Introduction 4 4.2.2 Character repertoire . .5 4.2.3 Separators . . 4.2.3.1 Element separators . .6 4.2.3.2 Parameter separators. 6 4.2.3.3 Comments in the archive file 7 4.2.4 Encoding of parameter types . .7 4.2.4.1 Integer-bo
7、und types . .7 4.2.4.2 Real-bound types . .8 4.2.4.3 String-bound types . .9 4.2.4.4 Enumerated types . 9 4.2.4.5 Derived types 9 4.2.5 Forming archive file element names .I5 4.2.5.1 Terms deleted .15 4.2.5.2 Words added .I5 4.2.5.3 Words used unabbreviated .I6 4.2.5.4 Abbreviations 16 4.2.5.5 Abbre
8、viating compound types . .17 4.2.5.6 Sentinel character sequence . .18 4.2.5.7 The derived archive file element names .18 4.3 Encoding the PHICS archive file elements . .22 4.3.1 Encoding delimiter elements 22 4.3.2 Encoding archive file descriptor elements . .22 4.3.3 The structure element producti
9、on .22 4.3.4 Encoding output primitive elements .26 4.3.5 Encoding attribute elements . .32 4.3.6 Encoding modelling transformation elements . .40 4.3.7 Encoding miscellaneous elements . .41 4.3.8 Encoding external elements .42 4.4 Clear-text encoding conformance. . 42 A Clear-text encoding-dependen
10、t formal grammar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 0 ISO/IEC 1997 All right5 reserved Unless otherwlse specified. no part of this publication may he reproduced or utilized in any form or by any means. electronic or mechanical, includ
11、ing photocopymg and microfilm. without permission in writmg from the pubIsher. ISO/IEC Copyright Oflice l Case postale S6 l CH- I2 I I Gent% 20 - Swltzcrlnnd Printed in Switzerland ii OISO/IEC ISO/IEC 9592-3: 1997(E) Foreword IS0 (the International Organization for Standardization) and IEC (the Inte
12、rnational Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of IS0 or IEC participate in the development of International Standards through technical committees established by the respective organization to deal with particular f
13、ields of technical activity. IS0 and IEC technical committees collaborate in fields of mutual interest. Other international organirations, o oovernmental and non-governmental, in liaison with IS0 and IEC, also take part in the work. In the field of information technology, IS0 and IEC have establishe
14、d a joint technical committee, ISO/IEC JTC I. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 c/o of the national bodies casting a vote. lnternational Standa
15、rd ISO/IEC 9592-3 was prepared by Joint Technical Committee ISO/IEC JTC I, Itlfor-mc/tior technology, Subcommittee SC 24, Computer gruphics and image processil7g. This second edition cancels and replaces the first edition (ISO/IEC 9592-3: 1989), which has been technically revised. It also incorporat
16、es Amendment I : 1992. ISO/IEC 9592 consists of the following parts, under the general title lnjiormatiorl technology - Computer graphics and irwge processirlg - ProgrammerS Hierarchical lrlteractive Graphics System (PHIGS): - Part 1: Furlctionul descriptiw7 - Part 2: Archive,file format - Part 3: S
17、pec SPACES in the actual archive file are indicated through the separator productions given in 4.3.3. e) The metasymbols used in describing the grammar do not appear in the actual archive file. 4.2 Archive file format 4.2.1 Introduction A clear-text encoding of a PHIGS archive file consists of a str
18、eam of characters forming a series of elements, each of which starts with an element name and ends with one of the element delimiters, either the SLASH character (also known as SLANT or SOLIDUS) or the SEMICOLON character. These characters do not act as element delimiters when occurring within the b
19、ounds of a string parameter, as defined below. The order of elements within a clear-text encoding of a PHIGS archive file is specified by ISO/IEC 9592-2. This specifies a formal grammar over the following eight symbols: BEGIN ARCHIVE FILE END ARCHIVE FILE BEGIN STRUCTURE END STRUCTURE ARCHIVE FILE V
20、ERSION ARCHIVE FILE DESCRIPTION STRUCTURE ELEMENT EXTERNAL ELEMENT Each of these symbols is treated as a non-terminal in the formal grammar that follows. Taken together, the formal 4 OISO/IEC ISO/IEC 9592-3:1997(E) Clear-text encoding format Archive file format grammar of ISO/IEC 9592-2 and this par
21、t of ISO/IEC 9592 provide a formal grammar for a PHIGS archive file over the ISOfiEC 646 character set. 4.2.2 Character repertoire In order that the metasymbols used in describing the grammar do not appear in the actual archive file, the character repertoire of the clear-text encoding will be limite
22、d to those characters enumerated below, except for string parameters, which, at the minimum, support the full ISO/IEC 646 character set and, optionally may include characters which shift into other character sets. Each string is assumed to start in the ISO/IEC 646 character set. Upper-case character
23、s: - Lower-case characters: “a”, “b”, I1c11, “d”, llell, “f, “g”, “h”, “i”, li”, “k”, “1”, l(mll, “n” Digits: ” ” (SPACE character) “+” (PLUS character) “-” (MINUS character) “#” (NUMBER SIGN) “;” (SEMICOLON character) “/” (SLASH, SLANT, or SOLIDUS character) “(” (LEFT or OPEN PARENTHESIS character)
24、 “)” (RIGHT or CLOSE PARENTHESIS character) “,” (COMMA character) “.” (DECIMAL POINT or PERIOD character) “ (APOSTROPHE or SINGLE QUOTE character) “” (DOUBLE QUOTE character) ” ” (UNDERSCORE character) “s” (DOLLAR SIGN or CURRENCY symbol) “%” (PERCENT SIGN character) Lower-case characters are consid
25、ered to be the same as upper-case characters when occurring outside of string parame- ters. Any combination of lower-case and upper-case characters may be used within an element or enumerated parame- ter name. The UNDERSCORE and DOLLAR SIGN symbols are defined as “null characters” within this encodi
26、ng. They may appear anywhere within an archive file, and are mandated to have no effect on parsing (outside of string parameters). They are available for the generator or editor of an archive file to use in enhancing readability of tokens. For example, the following are all equivalent: linetype, LIN
27、ETYPE, LineType, line-type, $LINETYPE, L-I-N-E$T-Y-P-E. The following are all equivalent: 123456, $123456, 123-456, $123-456, $12$34$56. Those control characters that are format effecters (BACKSPACE, CARRIAGE RETURN, LINEFEED, NEWLINE, HORIZONTAL TAB, VERTICAL TAB, and FORMFEED) are permitted in the
28、 archive file, but are treated as SPACE characters (that is, as soft delimiters) by the archive file interpreter whenever they occur outside of a string parameter. They may be used to assist in formatting the archive file to improve its readability. A PHIGS archive file written in the clear-text enc
29、oding is considered not to be a conforming interchange if it includes characters other than those listed in 5 ISO/IEC 9592-3:1997(E) OISO/IEC Archive file format Clear-text encoding format the repertoire and the format effecters (outside of string parameters). Implementation-dependent extensions whi
30、ch require use of characters other than the above should be embedded in the string parameters of the GSE or APPLICA- TION DATA elements, or in comments. The code set of the characters is not fixed by this part of ISO/IEC 9592. In order to accomplish the objective of edita- bility, it is permitted to
31、 encode the clear-text encoding using the character set codes native to the system. It is presumed that standard conversion facilities can be used in translating clear-text PHIGS archive files from one systems character set codes to another, consistent with the treatment of other text files being tr
32、ansferred between systems. The ISO/IEC 646 codes should be used to encode clear-text archive files for transport between diverse systems. Null characters or format effecters outside of text strings which do not exist in the target systems encoding may be dropped in such translation, and lower-case l
33、etters translated to upper case as necessary, without altering the informa- tion content of the archive file. Likewise, the two statement delimiter characters are interchangeable and may be changed in such a translation without affecting the information content of the archive file. The two string de
34、limiter characters are interchangeable, but any translation shall correctly handle the possible occurrence of either string delim- iter character within the string parameter. 4.2.3 Separators 4.2.3.1 Element separators - - The SEMICOLON and SLASH characters may be used to delimit elements in a clear
35、 text archive tile. These elements do not, however, terminate an element when they occur within a string parameter, as described in 4.2.4.3. The elements of the archive file are not terminated by the ends of records, as indicated by control characters such as CR (carriage return) or LF (linefeed). M
36、ultiple elements may exist on one line, and any element may extend over multiple lines. 4.2.3.2 Parameter separators The following productions are used in the clear-text encoding for parameter separators: .- - . .- - - - - - - - + * I Most commands require a SOFISEP after the element name (e.g., at
37、least one space). This permits element names to be formed from a mixture of alpha and numeric characters. The separator between parameters is usually a SEP. This format permits omission of parameters. (Two consecutive COMMAS indicate an omitted parameter.) Since the enclosing APOSTROPHE or DOUBLE QU
38、OTE character sufficiently delineates string parameters, and the statement delimiter SLASH also sets off the data on either side of it, the separators between these characters and adja- cent parameters or element names are optional (OPTSEP). SEPCHAR characters are not permitted within a name (elemen
39、t or enumerated type), or within the representation of a numeric parameter. Any place where a SEPCHAR is permitted (other than inside a string parameter), an arbitrary number of SEPCHARs may be used. 6 OISO/IEC Clear-text encoding format ISO/IEC 9592-3:1997(E) Archive file format 4.2.3.3 Comments in
40、 the archive file Comments may be included in a clear-text archive file to enhance its readability and usefulness. Some uses of com- ments might be to document hand-edited changes to the archive file, or as “notes to ones self made while reading an archive file. To include other forms of nongraphica
41、l information in an archive file, it is suggested that the EXTERNAL element be used. Comments are encoded as a series of printing characters and s surrounded by “%” (PERCENT SIGN) characters. The text of the comment may not include this comment delimiter character. Comments may be included any place
42、 that a separator may be used, and are equivalent to a ; they may be replaced by a SPACE character in parsing, without affecting the meaning of the archive file. 4.2.4 Encoding of parameter types 4.2.4.1 Integer-bound types Integers, integer coordinates and indices are all bound to signed integers,
43、indicated in the encoding as I. .- . .- I := 0 + .- - I .- - 0111213141516171819 := 0 + - - 213141516171819110111112113114115116 := IAIBICIDIEIFlalblcldlelf The null characters are permitted within numbers, but are not shown in the productions for simplicity. A decimal integer has an optional sign a
44、nd at least one digit. If the sign appears, it immediately precedes the number with no intervening SPACE (or other ) characters allowed. A based integer has an optional sign, a base (an unsigned integer in the range 216 inclusive, represented in base lo), a “#“, and a string of one or more extended
45、digits. If the sign appears, it immediately precedes the number with no inter- vening SPACE (or other ) characters allowed. The extended digits used shall be valid for the base named or the archive file is not conforming; e.g., for base 8 the digits “8”, “9”, etc. are not valid, for base 2 only the
46、digits “0” and “1” are valid, and so forth. Case is not significant for the extended digits. If the sign is omitted for either form, the number is considered non-negative. Both the base and the + are interpreted as unsigned numbers, and the final result negated if a MINUS SIGN preceded the number. N
47、o assumptions should be made as to the word size of the archive file retrieval process, or whether the underlying arithmetic is ones complement, twos complement, or sign-magnitude. For example, -1 would be encoded in hexadecimal as - 16#1, - 16#0001, etc. rather than 16#FFFF. Of course, archive file
48、s may be created util- izing prior knowledge of the intended target machine, but any such assumptions will limit the portability of archive files and are discouraged. The PHIGS functional data types “C”, “G2”, “G3”, “GS”, “AI”, “PI”, “EI”, “FN” and “WI” are represented by integers in this encoding.
49、Some examples are: 0,007, -5, + 123-456 The following are equivalent: 65535, 16#FFFF, 16#ffff,8#177777,2#111111111111111 The following are equivalent: -32-768, - 16#8000, -8#lOOOOO, -2# 1000000000000000 ISO/IEC 9592-3:1997(E) OISO/IEC Archive file format Clear-text encoding format Interpretation of numerically bound parameters will be “free field”, that is, there is an implied radix point to the right of the rightmost digit, and neither leading nor trailing spaces are significant. Leading zeroes are not significant. 4.2.4.2 Real-bound types Reals and real coordinate
