ANSI INCITS ISO 9069-1988 Information Processing - SGML Support Facilities - SGML Document Interchange Format (SDIF) (Adopted by INCITS).pdf

1、INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXflYHAPOAHAR OPrAHL43AMR I-IO CTAHAAPTM3Al it represents public text that is part of the document, but is not being inter- changed because the recipient is expected to have a copy. 4.

2、7 related document: An SGML document that is used in conjunction with a main document, but is not referenced as part of its content NOTE - Some examples are: - a covering letter; transmittBl form: - catalog card: formatting procedure: or document profile. 4.8 SDIF: SGML Document 4.9 SDIF identifier:

3、 A sequence number assigned to in the SDIF data stream. Interchange Format unique identifying an entity descriptor NOTE - It corresponds to the position of the entitys exter- nal identifier. For example, the entity descriptor with the SDIF identifier “5” represents the entity identified by the fifth

4、 markup declaration in the data stream that has an external identifier. 4.10 SDIF identifier reference: An entity descrip- tor that contains no text of its own, but instead refers to the SDIF identifier of another entity descriptor. It represents a duplicate declaration of an entity that either has

5、already occurred in the data stream, or that is omitted public text. 4.11 SDIF name: An SGML name assigned in the SDIF data stream to a document or to the data stream as a whole. 4.12 SDIF packer: A program that creates an SDIF data stream. NOTE - The parameters to an SDIF packer usually include the

6、 SDIF name for the data stream, the SDIF names and sys- tem identifiers for the main and related documents, and the order in which the documents should be packed. 4.13 SDIF unpacker: A program that decompos- es an SDIF data stream into its constituent enti- ties. NOTE - If necessary, the SDIF unpack

7、er will modify the sys- tem identifier parameter of markup declarations to be consis- tent with storage addresses in its environment. 4.14 SGML Document Interchange Format: A data structure that enables a main document and its related documents, each of which might be stored in several entities, to

8、be combined into a single data stream for interchange in a manner that will permit the recipient to reconstitute the separate entities. 5 Description of the data stream The SDIF data stream represents one or more SGML document entities, and zero or more SGML subdocument, SGML text, and data entities

9、, as defined in IS0 8879. NOTES 1 These entities comprise a main document, and zero or more related documents, that are to be interchanged together. Each of the documents is subject to its own SGML declaration, whose concrete syntax definition, limits on subdocument nesting, and other restrictions a

10、pply. 2 The application-specific information parameter of the SGML declaration can be used to identify whether the document con- forms to a particular document architecture. 5.1 Organization of the data stream The data stream consists of a field that identifies the character set used for markup thro

11、ughout the data stream, followed by document and entity descriptors that represent the main and related documents. NOTES 1 The formal definition can be found in clause 6. 2 SDIF serves solely to identify and delimit the separate docu- ments, and the entities into which the documents may be divid- ed

12、. No other information is represented directly in SDIF, except for the identification of the character set. In particular, SDIF has no information about the element structure of the documents, as this is found within the encapsulated SGML entities, which may also include layout and presentation info

13、rmation. The document descriptors are in the order speci- fied to the SDIF packer. NOTES 1 See 5.5 for the order of the entity descriptors 2 Documents that are not SGML documents, such as font defini- tions or formatting procedures, will require a simple SGML doc- ument as an identifying shell from

14、which they can be referenced as data entities. 5.2 Data stream character set This field contains one or more designating escape sequences for the data stream character set. The escape sequences shall be formulated in accor- dance with IS0 2022. NOTE - It is usually the originating system character s

15、et. 2 5 Description of the data stream IS0 9069:1988(E) 5.3 SDIF name The main document, related documents, and the data stream shall be assigned SDIF names when the data stream is created. NOTES 1 They do not have SGML entity names, as they are not refer- enced from an SGML document. 2 A documents

16、SDIF name is ordinarily derived from the docu- ments system identifier in the originating system. SDIF names shall conform syntactically to the rules of the SGML reference concrete syntax, and shall be coded in the data stream character set. No two SDIF names in the same data stream can be the same.

17、 NOTE - An application or architecture can establish conven- tions for SDIF names just as it can for names within an SGML entity. For example, an architecture could require that the SDIF name “PROFILE” be used for the related document that con- tains document, management attributes and similar infor

18、mation about the main document. An SDIF name can be accompanied by an explana- tory comment. 5.4 Document descriptor 5.4.1 Included entities A document descriptor contains an SGML docu- ment entitity as defined in IS0 8879. The external identifiers in its markup declarations, and in decla- rations o

19、ccurring in entities directly or indirectly referenced from it, determine the other entities for which entity descriptors will be included in the doc- ument descriptor. NOTES 1 If an external entity is a subdocument, descriptors for the external entities declared within it are also included, and so

20、on for any nested stbdocumnts. 2 Although a data entity contains no SGML markup, it could (in its own notation) contain references to other data entities or SGML subdocument entities. Entity descriptors for such entitles are Included in the data stream only if the entitles are declared in some SGML

21、entity that is Included in the data stream. No entity descriptor is included for the default enti- ty. NOTE - An effect of this sub-sub-clause is to require that there be an entity declaration for every entity that is to be included in the SDIF data stream, including entities referenced from data en

22、tities and entities whose references could otherwise have been defaulted. 5.4.2 Document character set The document character set shall be the same as the data stream character set. NOTE - A document character set is the only character set used for markup in a document. Any number of character sets

23、may be used for data, and they need not be the same for all documents in the data stream. 5.5 SDIF identifier NOTE - An SGML name is not sufficient for unique identifica- tion of an entity in the data stream because the same name can occur in more than one document or subdocument. Therefore, an SDIF

24、 identifier is assigned to each declared external entity in a manner that guarantees uniqueness and reflects the entity structure (in top-down, level-by-level order). The sequence numbers for SDIF identifiers are cod- ed in the data stream character set. They begin at 1, are incremented by 1, and ar

25、e assigned in the following manner: 4 b) cl d) A document descriptor is created for the first SGML document entity and its prolog is exam- ined for external identifiers. NOTE - The external identifiers can occur in entity, document type, link type, and notation declarations, but will be ignored in a

26、 default entity declaration. Entity descriptors are created for them, and SDIF identifiers assigned, in the order the dec- larations are encountered, until the end of the prolog is reached. The first SDIF identifier assigned in a prolog is recorded in the first identifier field. If none is assigned,

27、 the value recorded must be “0”. NOTE - The level-by-level traversal of the entity struc- ture is an efficient way to pack the data stream. The SDIF unpacker, however, may prefer a left list traversal in order to assign system identifiers efficiently. The first identifier field permits such a traver

28、sal by identifying the children of a given document or subdocument entity. The newly created entity descriptors are examined for a subdocument entity. If one is found, its prolog is scanned as above, and entity descriptors are created for any external identifiers found. When the end of a subdocument

29、 entity prolog is reached, searching and sequential number- ing resume in the prolog of the next encoun- tered subdocument entity, if any. When the end of the data stream is reached, searching and sequential numbering continue in the prolog of the next SGML document enti- ty, if any. 5.5 SD/F identi

30、fier 3 IS0 9069:1988(E) 5.6 Entity descriptor The type of entity descriptor is determined in the following manner: a) For the first occurrence of an external identifier in the data stream, if the entity text is to be inter- changed, an entity descriptor is created that contains the actual text; that

31、 is, the descriptor will include an SGML subdocument entity, an SGML text entity, or a data entity. b) For the first occurrence of an external identifier of text that is not to be interchanged, the entity descrip- tor will have no text; that is, it will be an omitted public text descriptor. Such an

32、external identifier shall be a public identifier. c) For occurrences of an external identifier after the first, the entity descriptor will be a cross-reference to the entity descriptor that represents the first occurrence of the external identifier; that is, it will be an SDIF identifier reference.

33、6 Abstract data stream format IS09069-SDIF DEFINITIONS : : = BEGIN Data-stream := SEQUENCE data-stream-character-set Character-set-designation, data-stream-name related-documents-A main-document related-documents-B Document-descriptor document-name first-identifier document-entity external-entities

34、Entity-descriptor entity-identifier entity-name subdocument-structure text-entity data-entity cross-reference omitted-public-text Subdocument-structure first-identifier subdocument-entity SDIF-name-and-description, APPLICATION 81 IMPLICIT SEQUENCE OF Document-descriptor OPTIONAL, APPLICATION 91 IMPL

35、ICIT Document-descriptor, APPLICATION lo IMPLICIT SEQUENCE OF Document-descriptor OPTIONAL I := APPLICATION 111 IMPLICIT SEQUENCE ( SDIF-name-and-description, SDIF-identifier, SGML-document-entity, SET OF Entity-descriptor OPTIONAL 1 := APPLICATION 121 IMPLICIT SEQUENCE ( SDIF-identifier, SGML-name,

36、 CHOICE Subdocument-structure, SGML-text-entity, External-data-entity, SDIF-identifier, NULL I I := APPLICATION 131 IMPLICIT SEQUENCE SDIF-identifier, SGML-subdocument-entity I 6 Abstract data stream format IS0 9069:1988(E) Character-set-designation External-data-entity SDIF-identifier SDIF-name-and

37、-description SGML-document-entity SGML-name SGML-subdocument-entity SGML-text-entity END 7 Encoding rules := APPLICATION 0 IMPLICIT OCTET STRING - Coded character string as in IS0 2022: - designating escape sequences := APPLICATION l IMPLICIT OCTET STRING - Coded character or bit string - conforming

38、 to the data content - notation specified by the SGML - entity declaration. := APPLICATION 21 IMPLICIT OCTET STRING - Coded character string as in IS0 8879: := ;P;%;ION 31 IMPLICIT OCTET STRING - Coded character string as in IS0 8879: - name, followed optionally by a - description of the named objec

39、t := APPLICATION 41 IMPLICIT OCTET STRING - Coded character string as in IS0 8879: - SGML document entity := APPLICATION 51 IMPLICIT OCTET STRING - Coded character string as in IS0 8879: - name := APPLICATION 61 IMPLICIT OCTET STRING - Coded character string as in IS0 8879: - SGML subdocument entity

40、 := APPLICATION 71 IMPLICIT OCTET STRING - Coded character string as in IS0 8879: - SGML text entity An SDIF data stream shall be encoded in the manner required by the interchange medium or communication system. Where more than one encoding is permitted, the choice shall be made by agreement of the

41、parties to the interchange. NOTE - It is strongly recommended that a system conforming to this International Standard be able to interchange an SDIF data stream that is encoded in accordance with the ASN.l basic encoding rules specified in IS0 8825. 7 Encoding rules 5 IS0 9069:1988(E) Annex A Relati

42、on to other standards (This annex does not form an integral part of this International Standard.) A.1 Message-handling standards Conforming SGML documents that are structured according to this International Standard can be transferred using the MOTIS functions defined in the following standards, and

43、 in other similar standards and CCITT Rec- ommendations. ISO/IEC 10021, information processing systems - Text communication - Message Oriented Text Inter- change System.” A.2 Office Document Architecture (ODA) The SGML Document Interchange Format is a conforming means of Open Systems Interchange for

44、 docu- ments that conform to the SGML representation of ODA documents defined in IS0 8613, Information processing - Text and office systems - Office Document Architecture (ODA) and interchange format.) A.3 OSI Presentation Services A.3.1 Object identifiers A.3.1.1 Abstract syntax This International

45、Standard assigns the ASN.l object identifier value iso standard 9069 abstract-syntax (1) as an abstract syntax name for the set of presentation data values, each of which is a value of the ASN.l type “IS09069-SDIF.Data-stream” defined in clause 6 The corresponding object descriptor value is “SDIF ba

46、sic abstract syntaxll NOTE - The specification of abstract syntaxes which support the transfer of only part of the SDIF semantics in each presentation data value is outside the scope of this international Standard. A.3.1.2 Transfer syntax The ASN.l object identifier and object descriptor values (joi

47、nt-iso-ccitt asnl (1) basic-encoding (1) and )IBasic Encoding of a single ASN.l type“ (assigned to an information object in IS0 8825) can be used as a transfer syntax name with this abstract syn- tax name. They identify the transfer syntax obtained by applying the ASN.l Basic Encoding Rules specifie

48、d in IS0 8825. NOTE - The specification and naming of alternative transfer syntaxes is outside the scope of this International Standard. 1) To be oubllshed. 6 A Relation to other standards IS0 9069:1988(E) A.3.2 OSI Document Type Definition This subclause identifies an OSI Document Type which can be

49、 used to carry SDIF semantics in FTAM (IS0 8571) and JTM (IS0 8832) transfers. NOTES 1 This subclause uses the term “document type” as it is used in conjunction with Open Systems Interconnection, not as defined in IS0 8079. 2 The subheadings below are the same as those used in other OSI standards for the definition of OSI Document Types prior to the establishment of a Registration Authority for OSI Document Types. A.3.2.1 Identifier The ASN.l object identifier value (iso standard 9069 document-type (2) basic (I) can be use