Definition

Aggregations shall not cross <Models> and/or <Environment Root>.

Rationale

Why would a generic <Model> use pieces of the terrain? If the <Model> is intended to be instanced as part of the terrain of the <Environment Root>, then <Environment Root> should instance the <Model>, not duplicate parts of it.

If a <Model> or <Environment Root> needs to use another <Model>, use a <Feature Model Instance> or <Geometry Model Instance>. If only a portion of the <Model> is desired for reuse, it should be a <Model> of its own.

Example

1. If a <Polygon> is under <Environment Root>, no <Model> can use the <Polygon>.
2. If a <Polygon> is under a <Model>, <Environment Root> cannot use the <Polygon> directly. A <Model>'s components can be accessed only via <Geometry Model Instances> and/or <Feature Model Instances>.
3. If a <Polygon> is under a <Model>, no other <Model> can use that <Polygon> directly. A <Model>'s components can be accessed only via <Geometry Model Instances> and/or <Feature Model Instances>.

FAQs