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Defect Report Number: 8632-1/056
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Submitter: Rosenthal
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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: 1 July 1995
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Deadline on response from editor: : 1 October 1995
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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, Functionalspecification.
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Qualifier (e.g. error, omission, clarification required): Technical
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References in document (e.g. page, clause, figure and/or table numbers):clause 5.5.4, D.4.4.1, PPF T.18.4, PPF T.25
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Nature of defect (complete, concise explanation of the perceived problem):
According to clause 5.5.4, TRANSPARENCY is implementation dependent. Profiles, by definition should give meaning to implementation dependent semantics. The Model Profile does not specify (in PPF T.18.4 nor IIR) how transparency and auxillary colour shall be interpreted.
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Solution proposed by the submitter (optional):
Either a) Prohibit the elements (TRANSPARENCY and AUXILLARY COLOUR) or b) Specify their interpretation. Add the following as an entry in the IIR. "The auxiliary colour appears as a ‘local background’ to the graphical primitives when they are drawn. When transparency is off, the auxiliary colour appears ‘behind’ the primitives. When tansparency is switched on, there is nothing drawn behind the primitive." I support alternative b) in principle. I propose that the quoted description of the effect to be achieved by interpreters should be modified so that it does not actually describe the effect, but rather points to existing CGM:1992 text. The desire is to nullify the last sentence of 5.5.4, therefore something in the IIR like the following would work fine: "Interpreters shall treat the auxiliary COLOUR and TRANSPARENCY elements as described in 5.5.4 paragraph 1, items a-d, and 5.5.4 paragraph 2."
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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):
Insert new 7.5.7.9 on p24: "7.5.7.9 Transparency
The PPF requires that profiles address the interpretation of transparency. The profile shall specify whether it is as described in the 2nd and 3rd paragraphs of the description in 5.5.4 or, if not, how transparency is implemented."
Create new entry at end of Table 25 on p106 In Functionality column insert: T.25.11 Transparency References 5.5.3 5.5.4 T.18.4 In Specification - PPF column insert: Same as Model Profile |_| If TRANSPARENCY permitted specify: In Specifications - Model Profile column insert: If TRANSPARENCY permitted specify: Interpreters shall implement the AUXILIARY COLOUR and TRANSPARENCY elements as described in the 2nd and 3rd paragraphs of the description in 5.5.4.
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