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1、BRITISH STANDARD BS 7567-3: 1992 Incorporating Amendment No. 1 Electronic transfer of geographic information (NTF) Part 3: Specification for implementing NTF using BS 6690 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy
2、, (c) BSI BS 7567-3:1992 This British Standard, having been prepared under the direction of the Information Systems Technology Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 May 1992 BSI 08-1999 The following BSI references relate to
3、the work on this standard: Committee reference IST/36 Draft for comment 91/65602 DC ISBN 0 580 20876 1 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Information Systems Technology Standards Policy Committee (IST/-) to Technical Committ
4、ee IST/36, upon which the following bodies were represented: Advanced Technology Marine Systems Association for Geographic Information B Ae Sema Ltd. Berkshire County Council British Telecommunications plc CAM Ltd. Cambridgeshire County Council Digital Equipment Co Ltd. Institute of Terrestrial Ecol
5、ogy Laser Scan Ltd. Local Government Management Board Logica UK Ltd. London Fire and Civil Defence Authority Ministry of Defence Ordnance Survey Royal Engineers Survey Royal Institution of Chartered Surveyors University of Edinburgh Amendments issued since publication Amd. No.DateComments 8919Decemb
6、er 1995 Indicated by a sideline in the margin Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7567-3:1992 BSI 08-1999i Contents Page Committees responsibleInside front cover Forewordii Section 1. General 1.1
7、Scope1 1.2Normative references1 1.3Definitions1 1.4Summary comparison of terms1 Section 2. BS 6690 implementation 2.1BS 6690 levels2 2.2Files2 Section 3. Description of BS 6690 field encodings 3.1General3 3.2Control details3 3.3Formats3 3.4Tags and labels3 3.5Splitting n-tuple/repetition records3 Se
8、ction 4. Implementation 4.1Data description definitions4 4.2NTF records common to all levels5 4.3NTF records for levels 1 and 28 4.4NTF records for level 311 4.5NTF records for level 416 4.6NTF records for level 520 Annex A (informative) Summary list of field descriptors21 List of referencesInside b
9、ack cover Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7567-3:1992 ii BSI 08-1999 Foreword This Part of BS 7567 has been prepared under the direction of the Information Systems Technology Standards Policy
10、 Committee. BS 7567-3:1992 specifies how NTF, a data transfer standard for a wide range of geographic data, is encoded in a media-independent form using BS 6690 A data descriptive file for information interchange (equivalent to ISO 8211). BS 7567-2:1992 may be used as an alternative to this Part by
11、agreement between the donor and recipient. It is essential for users of this Part to refer to Part 1 of BS 7567. In section 4, various subclauses are introduced but not used: this device is for the convenience of cross-referral between the implementation specifications for NTF levels 3 and 4. For ex
12、ample, a record for level 3 implemented in 4.4.6 is implemented for level 4 at 4.5.6. Section 4 in this Part corresponds exactly to section 4 of BS 7567-1:1992. For example, the record implementation specified at 4.4.6 of this Part has its syntax specified in 4.4.6 of Part 1. A British Standard does
13、 not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an insid
14、e front cover, pages i and ii, pages 1 to 22, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, Lon
15、don South Bank University, Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7567-3:1992 BSI 08-19991 Section 1. General 1.1 Scope This Part of BS 7567 specifies the procedures for the formatting of NTF Data Models, the interchange file structures and the detailed record interpretati
16、ons specified in Part 1 of BS 7567:1992 in accordance with BS 6690:1986. NOTESyntax is also specified for a minority of records which are implemented differently when BS 6690 is used instead of plain NTF. 1.2 Normative references This Part of BS 7567 incorporates, by reference, provisions from speci
17、fic editions of other publications. These normative references are cited at the appropriate points in the text and the publications are listed on the inside of the back cover. Subsequent amendments to, or revisions of, any of these publications apply to this Part of BS 7567 only when incorporated in
18、 it by updating or revision. 1.3 Definitions For the purposes of this Part of BS 7567, the definitions given in 1.3 of BS 7567-1:1992 apply together with the following additions and exceptions. 1.3.1 field an ordered sequential set of subfields NOTEAn NTF record as defined in BS 7567-1:1992 is repre
19、sented by either a single field or a set of sequential fields. 1.3.2 NTF level to distinguish “level” from its meaning within BS 6690, the term NTF level is used to represent its meaning in the context of BS 7567-1:1992 1.3.3 record a collection of related fields, independent of their physical repre
20、sentation on the medium of transfer 1.3.4 subfield a field as defined in BS 7567-1:1992 is redesignated as a subfield in this Part of BS 7567:1992 1.3.5 table a field which contains a two dimensional Cartesian label, where the first vector is null (see 6.2.3.2 of BS 6690:1986). That is, the “columns
21、” of the array are named and enumerated but the “rows” are not 1.4 Summary comparison of terms Two of the definitions in 1.3 differ from those used in Parts 1 and 2 of BS 7567:1992 to conform to those specified in BS 6690:1986. The terms affected are: Part of Standard13 Definitionplain NTF BS 6690 T
22、ermsrecord field one or more fields subfield Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7567-3:1992 2 BSI 08-1999 Section 2. BS 6690 implementation 2.1 BS 6690 levels At all levels of NTF, BS 6690 level
23、 3 shall be used (see 5.2.1.2 of BS 6690:1986). NOTEUse of level 3 enables those NTF records which are divided into several fields to be associated. 2.2 Files 2.2.1 General A transfer set shall consist of a volume header file, which is associated with a database description file for each database, e
24、ach of which is associated with one or more section files. On sequential media, these shall be ordered so that the volume header file is first, followed by the database description file for the first database, followed by the section files for that database, followed by the database description file
25、 for the next (if any) database, etc. BS 6690 specifies the method for writing files to standard media. Where an NTF record is defined as a series of BS 6690 fields, these fields shall be transferred in the order specified in section 4. NOTEOn non-sequential media, either file naming conventions sho
26、uld be used to make it clear how the files are interrelated, or extra documentation should be supplied giving this information. 2.2.2 The volume header file The volume header file shall comprise a single record containing a BS 6690 record identifier (0001) field, followed by a volume header (VOLH) f
27、ield, followed by zero or more comment (COMM) fields. 2.2.3 The database description file The database description file shall start with a record containing a BS 6690 record identifier (0001) field, followed by a database header (DBHR) field. This may be followed by one or more database description
28、records, each containing a BS 6690 record identifier (0001) field, followed by the relevant database fields. 2.2.4 The section file The section file shall start with a record containing a BS 6690 record identifier (0001) field, followed by a section header (SECH) field. This shall be followed by one
29、 or more section data records, each containing a BS 6690 record identifier (0001) field, followed by the relevant data fields. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7567-3:1992 BSI 08-19993 Section
30、 3. Description of BS 6690 field encodings 3.1 General The encoding of each BS 6690 field is specified in this Part using a simple textual notation that may be automatically translated into a BS 6690 data description for the field. The notation used within this Part is specified in 4.1. 3.2 Control
31、details The following control details shall be implemented for the data descriptive record leader (see 5.2.1 of BS 6690:1986): a) the BS 6690 interchange level shall be 3 (indicating that the fields within the transfer set are arranged in a hierarchical or tree structured manner); b) The inline code
32、 extension indicator shall be a space; c) The application indicator shall be a space; d) The field control length shall be 06; e) The coded character set indicator shall be three spaces; f) The size of the field tag field shall be defined as 4 characters in the entry map. 3.3 Formats NTF field forma
33、ts translate to BS 6690 subfield format statements as follows: a) Real numbers include a decimal point. The information about where the decimal goes is not indicated by the BS 6690 format, and shall be interpreted in accordance with section 4 of BS 7567-1:1992. b) Dates are treated as character fiel
34、ds since they do not directly match any specific BS 6690 format and shall be interpreted in accordance with section 4 of BS 7567-1:1992. 3.4 Tags and labels Field tags and subfield labels shall be four characters long and constrained to alphabetical and numerical characters. A correspondence table f
35、or NTF record descriptors and tag names is provided at Annex A. 3.5 Splitting n-tuple/repetition records Where the NTF record includes repeating fields, it shall be represented as two or more BS 6690 fields. NOTESeveral commonly used NTF records are composed of a simple series of items followed by a
36、 table of items: For example, in GEOMETRYx the “stem” is formed of the geometry identifier and the geometry type, and the rows of the table are the X, Y and possibly Z values. BS 6690 cannot represent this structure. Therefore the NTF record is split into two BS 6690 fields: the initial “stem” follo
37、wed by an array field to store the row data. NTFBS 6690 In An A* Ra,b Dn I (n) A (n) A R (a + 1) A (n) stemtable: row1 table: row2 table: row3 . . . Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7567-3:199
38、2 4 BSI 08-1999 Section 4. Implementation of NTF records 4.1 Data description definitions 4.1.1 General The following data description definitions and fields specific to the method of encoding shall be used in the field specifications in this section. See 6.2 of BS 6690:1986 for the specification of
39、 the elements of data fields. 4.1.2 Tag A field definition shall start with the definition of its tag: 4.1.3 Subfield Each subfield within a field shall be defined as: 4.1.4 Field termination A field definition shall be terminated by END within the notation. NOTEThis should not be confused with the
40、field terminator character FT which is required to mark the end of BS 6690 data fields. 4.1.5 Conventions of the encoding Where several fields are required to represent an NTF record the first field shall be the “parent” of the others and the later fields shall follow immediately after it. In sectio
41、n 4 each NTF logical record is specified by two subclauses: a) the BS 6690 encoding of the field or fields used to represent the NTF logical record; b) implementation details where needed. 4.1.6 Additional fields Two basic fields are always defined. The first shall be the 0000 field (see 5.2.3.1 of
42、BS 6690:1986) (with the field description being replaced by the files name in the actual BS 6690 data) and the second is the 0001 field (see 5.2.3.2 and 5.5.3.1 of BS 6690:1986). For example: TAG tagptagpg fieldname where TAG tag ptag pg fieldname indicates that this is a tag definition line. is the
43、 fields tag. is the tag of the parent of this field. are the printable graphics, used for UT and FT, normally ; 1 to 5 7NVERR5 NTFVER NTF version number; 2.0 END 4.2.3.2 Implementation details None. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:26:13 GMT+00
44、:00 2006, Uncontrolled Copy, (c) BSI BS 7567-3:1992 6 BSI 08-1999 4.2.4 Database header recordDBHREC 4.2.4.1 Field and subfield encoding TAG DBHR0001; ocompulsory but may contain a null value; tan optional trailing subfield. Licensed Copy: London South Bank University, London South Bank University,
45、Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7567-3:1992 BSI 08-199921 Annex A (informative) Summary list of field descriptors The following table lists the NTF mnemonic, the record name and the BS 6690 field tag. NTF Record Mnemonic NTF Record nameField tags ParentConstituent V
46、OLHDREC DBHREC DATADESC FEATCLASS DBQUAL SECHREC QUALREC SECQUAL NAMEREC NAMPOSTN CURVTEXT ATTREC POINTREC NODEREC EDGEREC FACEREC GEOMETRY1 GEOMETRY2 LINEREC CHAIN CLINE POLYGON AREA CPOLY COLLECT ATTDESC ATTCOM CODELIST TEXTREC TEXTPOS TEXTREP EXTERNAL COMMENT Volume header Database header Data de
47、scription Feature classification Database quality Section header Data quality Section quality Name Name position Curved text Attribute Point Node Edge Face 2-d geometry 3-d geometry Line Directed chain Complex line Polygon Area Complex polygon Collection of features Attribute description Attribute c
48、ombine Code list Text Text position Text representation External feature Comment VOLH DBHR DDSC FEAC DBQA SECH QUAL SECQ NAME NAMP CURV ATTR POIN NODE EDGE FACE GEOM GEOM LINE CHAI CLIN POLY AREA CPOL COLL ATTD ATTC CODE TEXT TPOS TXRP EXTE COMM ORNT PNATa LNKS CHFA CRD2 CRD3 LNED, LNATa CHGD CLAT P
49、LAT ARFC, ARAT POLS, CPAT COLI, COAT CODD TXNA, TXAT TREP EXAT a PNAT and LNAT are only used at levels 3 and 4. LNED is only used at level 4. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 22 blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:26:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7567-3:1992 BSI 08-1999 List of references (see 1.2) Normative references BSI Standards publications BRITISH STANDARDS INSTITUTION,