For first edition files, only one EXPRESS schema together with an optional ASN.1 object identifier of the schema version can be listed here. Specifies one or several Express schema governing the information in the data section(s). authorization the name and mailing address of the person who authorized this file.originating_system the name of the system and its version which originally created the information contained in this STEP-file.preprocessor_version the name of the system and its version which produces this STEP-file.organization the organization to whom the person belongs to.author the name and mailing address of the person creating this exchange structure.T11:57:53 for 27 of December 2003, 2 minutes to noon time. The time is given in the international data time format ISO 8601, e.g. time_stamp indicates the time when this file was created.There is no strict rule how to use this field. It may correspond to the name of the file in a file system or reflect data in this file. The values '3 1' and '3 2' indicate extended STEP-Files as defined in the 2001 standard with several DATA sections, multiple schemas and FILE_POPULATION support. The value '2 2' enforcing external mapping is also possible but only very rarely used. Often, one will find here the value _'2 1'_. The conformance option is either "1" for internal and "2" for external mapping of complex entity instances. Possible versions are "1" for the original standard back in 1994, "2" for the technical corrigendum in 1995 and "3" for the second edition. The version and conformance option of this file. Except for the data fields time_stamp and FILE_SCHEMA all fields may contain empty strings. The HEADER section has a fixed structure consisting of 3 to 6 groups in the given order. #19=APPLIED_ORGANIZATION_ASSIGNMENT(#10,#20,(#16)) Īs seen in the above example, the file is split into two sections following the initial keyword ISO-10303-21 : #12=APPLICATION_CONTEXT('mechanical design') #11=PRODUCT_DEFINITION_CONTEXT('part definition',#12,'manufacturing') * description */ ('A minimal AP214 example with a single part'),įILE_SCHEMA (('AUTOMOTIVE_DESIGN ')) In practice, however, most implementations only use a single data section (1st edition encoding). The 2nd edition allows multiple data sections to be used.In practice, however, SHORT NAMES are rarely used. The 1st edition of part 21 enforces the use of so-called SHORT NAMES, which are optional in the 2nd edition.In theory this would allow better AP interoperability, since a postprocessor may know how to handle some supertypes, but may not know the specified subtypes. Conformance class 2, which is not used in practice, always enforces the external mapping.Conformance class 1 is always used enforce the so-called internal mapping, which is more compact.They differ only in how to encode complex entity instances. Part 21 defined two conformance classes.The third edition, ISO 10303-21:2016, added anchor, reference and signature sections to support external references, support for compressed exchange structures in a ZIP-based archive, digital signatures, and UTF-8 character encoding.The second edition, ISO 10303-21:2002, included the corrigendum and extensions for several data sections.Therefore, it is recommended that users study the second edition instead (see below). The first edition, ISO 10303-21:1994, had some bugs, which were corrected by a Technical Corrigendum.
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