Section 3 - Classification of Metafiles

This specification establishes the requirements for the communication or interchange of graphical picture data in digital format for use by applications in the petroleum E&P application community. The CGM Profile defined by this specification addresses three interchange components: the metafile, the generator, and the interpreter.

Metafiles conforming to this profile shall identify and classify themselves within each of three categories:

1. level of functionality;

2. colour capability;

3. utilization of the CGM extensions defined in this profile.

3.1 Level of functionality

There are 2 levels of functionality classification for metafiles defined in this Volume 1. These levels are:

• PIP/I;

• PIP/II.

A metafile may be a conforming PIP/I metafile, or a conforming PIP/II metafile. Throughout this document, when PIP is used alone without a modifier, then it applies to both PIP/I and PIP/II.

At the time of release of this document, Volume 2 defines a third level, PIP/III, and a fourth level, PIP/IV.

3.2 Colour classification

There are 3 levels of colour classification for metafiles. These levels are:

• monochrome (black & white, or other bi-level);

• grayscale;

• full colour.

  A metafile may be a conforming monochrome metafile, or a conforming grayscale metafile, or a conforming full colour metafile. The requirements given later in this specification define the meaning and restrictions of each of these three colour classification levels for PIP metafiles.

  3.3 Utilization of extensions

  There are two levels of metafile classification related to extensions:

  • basic: the metafile contains only standard functions of CGM plus the ESCAPEs defined in section 4.3.9 of this profile; none of the ESCAPEs and GDPs defining application community extensions are included.

  • extended: the metafile possibly contains the extended functions, ESCAPE and GDP elements, defined in this profile.

  According to this classification category, a PIP metafile may be a conforming basic PIP metafile or a conforming extended PIP metafile.

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