Definition

1. For any perimeter-related organization,

   1.1	The regions defined by its branches shall not overlap; that is, the <Perimeter Data> on the branches shall define regions that do not overlap.
   1.2	For each branch of the organization, every primitive within that branch shall have a spatial extent overlapping that of the branch.

2. Consider a perimeter-related organization PRA, which is either <Perimeter Related Features> or a <Perimeter Related Geometry>.

   2.1	If PRA's strict_organizing_principle = SE_TRUE, then for each branch of PRA, each primitive within the branch shall have a spatial extent fully contained within that defined by the <Perimeter Data> corresponding to the branch. If PRA's strict_organizing_principle = SE_FALSE, then no guarantees exist as to how accurately the objects of the component tree rooted at PRA were placed into their "sorted bins" (the branches of PRA), apart from that specified by 1 (above).
   2.2	If PRA is a <Perimeter Related Features>, and the same <Feature Representation> instance belongs to more than one of its branches, then the unique_descendants and strict_organizing_principle flags of PRA shall be set to SE_FALSE.
   2.3	If PRA is a <Perimeter Related Geometry>, and the same <Geometry Representation> instance belongs to more than one of its branches, then the unique_descendants and strict_organizing_principle flags of PRA shall be set to SE_FALSE.

Rationale

1. In a hypothetical perimeter-related organization with overlapping <Perimeter Data>, determining which branch a given object belongs to would be ambiguous, so that the usefulness of the Perimeter Related Organizing Principle as a means of organizing primitives would be defeated.

2. Each branch of a perimeter-related organization is intended to organize objects that fall within the specified perimeter for that branch.

3. For perimeter-related organizations that interact with topology, the regions defined by the <Perimeter Data> are intended to fully partition the topological surface.

4. The strict_organizing_principle flag of <Perimeter Related Features> and <Perimeter Related Geometry> was designed to allow the use of perimeter-related organization, even when a few primitives cross the boundaries of the organizing principle.

Example

1. Consider a <Perimeter Related Geometry> PRG with two branches, each with a distinct component <Union Of Primitive Geometry> as shown in the diagram below.

   

   By the <<Perimeter Related Organizing Principle>>, at least one of the vertices of A shall fall within the region described by the <Perimeter Data> PD1. If PRG has strict_organizing_principle == SE_TRUE, then ALL the vertices of A shall do so.

2. Consider a second <Polygon> B, a sibling of A within UPG1. B falls on the boundary dividing the regions described by PD1 and PD2, such that at least one of B's vertices falls within PD1 and at least one of B's vertices falls PD2.

   By the <<Perimeter Related Organizing Principle>>, PRG's strict_organizing_principle flag shall be set to SE_FALSE, since branches are present which do not fully contain their objects.

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