1、 Reference numberISO/PAS 17684:2003(E)ISO 2003PUBLICLY AVAILABLE SPECIFICATION ISO/PAS17684First edition2003-12-01Transport information and control systems In-vehicule navigation systems ITS message set translator to ASN.1 format definitions Systmes de commande et dinformation des transports Systmes
2、 de navigation dans les vhicules Traducteur de lensemble des messages ITS en dfinitions de format ASN.1 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/PAS 17684:2003
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6、O 2003 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the
7、 country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2003 All rights reservedCopyright International Organization for Standardization Provided by IHS unde
8、r license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/PAS 17684:2003(E) ISO 2003 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 1 4 Message Set Tabular Form description 2
9、 4.1 General. 2 4.2 MSTF description 2 5 Specification of Descriptor Normal Form (DNF) 7 5.1 General. 7 5.2 Overview of DNF . 8 5.3 DNF Notation . 8 5.4 DNF character set . 10 5.5 DNF items. 11 5.6 Simple types 14 5.7 Enumerated types . 18 5.8 Complex types. 18 5.9 Defined types. 20 5.10 Structure o
10、f a DNF specification . 20 5.11 Summary of the EBNF productions for DNF 21 5.12 Translation of DNF to ASN.1 22 Annex A (informative) Sample Encoding in MSTF 24 Annex B (informative) ASN.1 Reserved Words . 28 Annex C (informative) A Comparison of DNF to ASN.1 29 Copyright International Organization f
11、or Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/PAS 17684:2003(E) iv ISO 2003 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national sta
12、ndards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International or
13、ganizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules give
14、n in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 7
15、5 % of the member bodies casting a vote. In other circumstances, particularly when there is an urgent market requirement for such documents, a technical committee may decide to publish other types of normative document: an ISO Publicly Available Specification (ISO/PAS) represents an agreement betwee
16、n technical experts in an ISO working group and is accepted for publication if it is approved by more than 50 % of the members of the parent committee casting a vote; an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical committee and is accepted for publ
17、ication if it is approved by 2/3 of the members of the committee casting a vote. An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is confir
18、med, it is reviewed again after a further three years, at which time it must either be transformed into an International Standard or be withdrawn. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible f
19、or identifying any or all such patent rights. ISO/PAS 17684 was prepared by Technical Committee ISO/TC 204, Intelligent transport systems. Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without lice
20、nse from IHS-,-,-ISO/PAS 17684:2003(E) ISO 2003 All rights reserved vIntroduction Working Group 11 of the Technical Committee ISO/TC 204 is responsible for the ITS information concerning navigation and route guidance. This committee, during the preparation of ISO 15075, Transport information and con
21、trol systems In-vehicle navigation systems Communications message set requirements, realized that the ISO/IEC directives require a formal description by ASN.1 whenever an information data structure, such as message set, is defined. ASN.1 is a well-defined language with significant descriptive power;
22、 however, due to the simplicity of almost all messages used in navigation and route guidance systems, they can be more simply expressed in tabular form. Since it is a common practice among navigation system engineers to define a message set by tables, the main part of this document specifies message
23、s as tables. Faced with the situation of different types of descriptions for a message set, one practical and the other formal, ISO/TC 204 started a project that bridges these descriptions instead of writing down one ASN.1 description for ISO 15075. This document, which allows engineers to write mes
24、sage sets for navigation and route guidance in a tabular form that is automatically translated to ASN.1 description, is a result of that project. In many navigation systems, traffic and travel information is transferred to and from vehicles and traffic information centers via transmitted messages. T
25、o make on-board navigation units compatible with navigation facilities, each message used in the system has to be precisely defined. The internationally accepted Abstract Syntax Notation One (ASN.1) is a powerful tool for describing information data structures. ISO/IEC has agreed that data structure
26、s, such as a message set, which define a standard should be formally described in ASN.1. As a consequence, ISO/TC 204 decided that information data structures such as the format of messages including navigation messages must be defined in ASN.1. Navigation engineers, however, usually use much simple
27、r tabular forms to describe their message sets. As the degree of complexity required in descriptions of navigation message sets does not require the full descriptive power of ASN.1, it was easy to imagine that some subset of ASN.1 could be defined for a simpler description of navigation message sets
28、. Therefore, the first task was to define the subset of ASN.1 most suitable for this purpose. However, instead of directly extracting a subset of ASN.1, an intermediate language, DNF (Descriptor Normal Form; see Clause 5), was proposed. The intermediate DNF language must retain its compatibility wit
29、h ASN.1, but can be simplified since most of the messages used in navigation are linear in the sense that they are simply written in the lines of a table. Thus, the descriptive power of DNF is strictly limited and any description defined by DNF should also be defined by ASN.1. This means that the se
30、t of all possible DNF descriptions is a subset of descriptions available in ASN.1. In this sense, DNF is a subset of ASN.1. The bridge between the simple DNF tabular descriptions and their respective formal ASN.1 descriptions is a compiler “dnf2asn1”. As shown in the following figure, a DNF descript
31、ion is translated to ASN.1 description by the compiler “dnf2asn1.” Figure 1 Function of the bridge compiler dnf2asn1 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/P
32、AS 17684:2003(E) vi ISO 2003 All rights reservedWith this compiling path, any navigation message set that is described in DNF is automatically converted to an ASN.1 description. By inserting an additional processing step prior to DNF, e.g. inserting another language definition and its compiler to DN
33、F, a message set described in the new language can be converted to first DNF by the new compiler and then to ASN.1 by dnf2asn1. In this way, an ASN.1 description of the original message set is generated. If the new language is based on a tabular form, then this double-bridge system can convert a tab
34、ular-form description of a message set to its ASN.1 equivalent. It is well known that the tabular form description of message set is much easier for navigation engineers to understand, define and maintain. However, the type of tabular form which best serves this purpose has not yet been clearly defi
35、ned. Therefore, this document presents an example of a tabular-form message-set description language and its compiler to DNF. Many aspects of the language were kept open for user definition so that descriptive features could be flexibly changed. As this tabular form message set/compiler is an exampl
36、e, it may not accommodate all the needs of a user, and thus it is recommended that a more specific message set/compiler be generated. Figure 2 Conversion of the tabular-form navigation message set into ASN.1 Copyright International Organization for Standardization Provided by IHS under license with
37、ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-PUBLICLY AVAILABLE SPECIFICATION ISO/PAS 17684:2003(E) ISO 2003 All rights reserved 1Transport information and control systems In-vehicule navigation systems ITS message set translator to ASN.1 format definitions 1
38、 Scope This Publicly Available Specification specifies a method that can be used to define navigation message sets in tabular form with a subsequent translation into a corresponding ASN.1 description. An intermediate language called Descriptor Normal Form (DNF), which is a subset of ASN.1, is specif
39、ied and used as an intermediate description between a tabular form and its ASN.1 description. A tabular-form message-set description language called Message Set Tabular Form (MSTF) is included as an example of a tabular form definition. 2 Normative references The following referenced documents are i
40、ndispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO/IEC 8824-1:1998, Information technology Abstract Syntax Notation One (ASN.1): Specifi
41、cation of basic notation Part 1 ISO/IEC 10646-1:2000, Information technology Universal Multiple-Octet Coded Character Set (UCS) Part 1: Architecture and Basic Multilingual Plane 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. The following terms
42、are defined in ISO/IEC 8824-1:1998 specification, bit string type, boolean type, character, character string types, choice types, component type, encoding, (ASN.1) encoding rules, enumerated types, false, integer type, module, null type, octetstring type, real type, recursive definitions, selection
43、types, sequence types, sequence-of types, spacing character, simple type, tag, true, type, type reference name, value, value set, white-space. 3.1 DNF character set set of characters used in the DNF notation NOTE See 5.4. 3.2 floating-point number number capable of being specified by the formula M 1
44、0E where M and E are two integers called the mantissa and the exponent, respectively Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ISO/PAS 17684:2003(E) 2 ISO 2003 All
45、rights reserved3.3 floating-point type type consisting of all possible floating-point numbers plus the two values + and - NOTE The floating-point type is a subset of the real type in ASN.1. The real type accommodates bases other than 10. 3.4 items named sequences of characters from the DNF character
46、 set which are used to form the DNF notation NOTE See 5.4. 4 Message Set Tabular Form description 4.1 General Message Set Tabular Form (MSTF) describes a message set by message components. A message component is defined by a line or lines, where a line consists of a sequence of boxes or cells. Each
47、cell contains either a string of characters or is empty. A string of characters contained in a cell may be one of the following component items: a reserved word; a data type; a data item; a special indicator composed of one or two special characters; a comment denoted by the special indicator “/”at
48、the beginning of the comment character string. Some of the data items used in MSTF are DNF identifiers (see 5.5.2). These component items are arranged in cells to form a line in accordance with the rules for MSTF line format, and then the lines are structured to form a message component in MSTF. Maj
49、or message components are structured in a block of lines where a block is separated by a line of empty cells. The first message component of a message set is the TITLE component. 4.2 MSTF description 4.2.1 Character set The characters that can appear in MSTF are the same characters used in DNF (see 5.4.1). 4.2.2 Special indicators The following indicators, specified b
