Definition

DRM objects are constrained in taking associate DRM objects as follows.

1. Let M be a <Model> instance.

   1. Let M have a <Feature Model> component F, and let F1 be a <Feature Representation> instance in the component tree of F and T be a <Feature Topology> instance in the component tree of F.

      1. F1 shall not associate to a <Feature Representation> instance outside the component tree of F.

      2. No <Feature Representation> instance outside the component tree of F shall associate to F1.

      3. F1 shall not associate to a <Feature Topology> instance outside the component tree of F.

      4. No <Feature Topology> instance outside the component tree of F shall associate to F1.

      5. T shall not associate to a <Feature Topology> instance outside the component tree of F.

      6. No <Feature Topology> instance outside the component tree of F shall associate to T.

   2. Let M have a <Geometry Model> component G, and let G1 be a <Geometry Representation> instance in the component tree of G and T be a <Geometry Topology> instance in the component tree of G.

      1. G1 shall not associate to a <Geometry Representation> instance outside the component tree of G.

      2. No <Geometry Representation> instance outside the component tree of G shall associate to G1.

      3. G1 shall not associate to a <Geometry Topology> instance outside the component tree of G.

      4. No <Geometry Topology> instance outside the component tree of G shall associate to G1.

      5. T shall not associate to a <Geometry Topology> instance outside the component tree of G.

      6. No <Geometry Topology> instance outside the component tree of F shall associate to T.

   3. Let M have both a <Feature Model> component F and a <Geometry Model> component G. Let F1 be a <Feature Representation> instance in the component tree of F and let G1 be a <Geometry Representation> instance in the component tree of G.

      1. F1 shall not associate to a <Geometry Representation> instance outside the component tree of G.

      2. No <Geometry Representation> instance outside the component tree of G shall associate to F1.

      3. G1 shall not associate to a <Feature Representation> instance outside the component tree of F.

      4. No <Feature Representation> instance outside the component tree of F shall associate to G1.

   4. Let M have an <Interface Template> component T.

      1. For every <Variable> instance V in the component tree of M, V shall associate exactly once with T.

      2. If V is a <Variable> instance that does not appear in the component tree of M, T shall not associate with V.

   5. Let M have a <Feature Model> component F, and let X be an instance of <Feature Model Instance> in the component tree of M. X shall not associate to F.

   6. Let M have a <Geometry Model> component G, and let X be an instance of <Geometry Model Instance> in the component tree of M. X shall not associate to G.

2. Let R be an <Environment Root> instance.

   1. Let R2 be an <Environment Root> instance, where the srf_context_info of R does not match that of R2.

      1. Let R have a <Feature Hierarchy> component F, and let X be a <Feature Representation> instance in the component tree of F. Let R2 have a <Feature Hierarchy> component F2, and let X2 be a <Feature Representation> instance in the component tree of F2. X shall not associate to X2, and X2 shall not associate to X.

      2. Let R have a <Geometry Hierarchy> component G, and let Y be a <Geometry Representation> instance in the component tree of G. Let R2 have a <Geometry Hierarchy> component G2, and let Y2 be a <Geometry Representation> instance in the component tree of G2. Y shall not associate to Y2, and Y2 shall not associate to Y.

      3. Let R have a <Feature Hierarchy> component F, and let X be a <Feature Representation> instance in the component tree of F. Let R2 have a <Geometry Hierarchy> component G2, and let Y2 be a <Geometry Representation> instance in the component tree of G2. X shall not associate to Y2, and Y2 shall not associate to X.

   2. Let R have an <Interface Template> component T.

      1. For every <Variable> instance V in the component tree of R, V shall associate exactly once with T.

      2. If V is a <Variable> instance that does not appear in the component tree of R, T shall not associate with V.

Rationale

Consider the <Feature Representation> with <Geometry Hierarchy> association. This association means that the <Feature Representation> is an alternate representation of the <Geometry Hierarchy>. A terrain <Feature Representation> represents some part of the terrain, not a part of some <Model>; a <Model> feature represents some abstraction of the <Model> rather than a feature of the terrain.

Example

1. Consider a transmittal with an <Environment Root> instance R and a <Model Library> instance L. Let "F15" be a <Model> component of L, under which <Polygon> instances exist. No <Feature Representation> instance under R may associate with an "F15" <Polygon> instance, since a terrain <Feature Representation> instance cannot at the same time represent a generic "F15" <Polygon> instance.

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