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Defect Report Number: 8632-1/066

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Submitter: Henderson

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Addressed to: JTC1/SC 24/WG 6 Rapporteur Group on ISO/IEC 8632, CGM

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WG secretariat: NNI

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Date Circulated by WG secretariat: 21 July 1998

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Deadline on response from editor: : 3 August 1998

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Defect Report concerning IS 8632:1992 Computer Graphics: Metafile for the storage and transfer of picture description information (CGM) Part 1, Functional

specification.

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Qualifier (e.g. error, omission, clarification required): Correction

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References in document (e.g. page, clause, figure and/or table numbers): AM2:1995 (AM1:1994), PICTURE DIRECTORY element in PPF, p.27, T.16.24; APPLICATION STRUCTURE DIRECTORY element, p.29, T.17.20.

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Nature of defect (complete, concise explanation of the perceived problem):

The Model Profile (T.16.24, p.27 of AM2:1995) has the PICTURE DIRECTORY element as 'permitted', with no other constraints. CGM:1992 AM2:1995 does not required that the Picture Directory be complete if present, i.e. that it contain an entry for every picture in the metafile. This is appropriate, as uses can be postulated for partial directories, and some profiles might standardize the meaning of such a partial directory (e.g., to point to some category of picture). However, no meaning is postulated for partial directories in the Model Profile. Therefore the directory is useless to interpreters, if a conforming MP metafile may have a partial directory — interpreters must scan the whole metafile anyway. The MP is supposed to encapsulate reasonable good practice, and provide guidance for profile writers who do not otherwise have requirements to deviate from the MP. Therefore the MP should require that Picture Directories be complete.

This also applies to T.17.20, p.29, APPLICATION STRUCTURE DIRECTORY. The MP should require that APS Directories be complete.

 

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Solution proposed by the submitter (optional):

T.16.24, p.27, add to the MP and the PPF sides of the table:

"If present, shall PICTURE DIRECTORY elements be complete, i.e., have an entry for every picture in the metafile? (yes/no)

If "no", describe any special meaning associated with those entries which appear in PICTURE DIRECTORY elements which are incomplete."

For the MP side of the table, add "yes" after the question. For the PPF side, blank.

T.17.20, p.29, add to the MP and the PPF sides of the table:

"If present, shall APPLICATION STRUCTURE DIRECTORY elements be complete, i.e., have an entry for every application structure in the picture? (yes/no)

If "no", describe any special meaning associated with those entries which appear in APPLICATION STRUCTURE DIRECTORY elements which are incomplete."

For the MP side of the table, add "yes" after the question. For the PPF side, blank.

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Editor's response (any material proposed for processing as a technical corrigendum to, an amendment to, or a commentary on the International Standard or DIS final text is attached separately to this completed report):

Amend the standard as proposed above.