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Precedence Rules
Precedence rules for your idealizations and connections determine which modeling entity takes precedence when you apply two modeling entities of the same type on or between the same reference entities. There are two types of precedence rules, modeling precedence rules and geometric precedence rules.
Modeling Precedence Rules
These rules apply when you work with assemblies, and are determined by the assembly hierarchy:
When you apply a modeling entity from a top-level assembly, this modeling entity takes precedence over a modeling entity applied from a subassembly or a part.
When you apply a modeling entity from a subassembly, this modeling entity takes precedence over a modeling entity applied from a part.
Geometric Precedence Rules
Keep these rules in mind when working with the modeling entities that require points, curves, or surfaces as their reference entities. With some of these modeling entities, you can use multiple geometric entities as reference entities. For example, you can select a feature or a pattern of points and create a beam, spring, or rigid link that runs along a sequence of points. You can also apply a beam on multiple curves, or place a shell on a collection of surfaces.
If you later create a new modeling entity of the same type, placing it on or between the same reference entities, it overrides the existing one when the following conditions are met:
You select a higher precedence geometric entity as a reference entity for your new modeling entity.
The higher precedence geometric entity belongs to a lower precedence geometric entity already referenced by your existing modeling entity.
For example, if you select a single point as a reference entity for your new beam, the new beam overrides an existing one that references a feature of points that include this single point.
The following table illustrates how the precedence rules work for modeling entities that can reference points, curves, or surfaces.
 Modeling Entity or Mesh Control Reference Entity Geometric Precedence Rule • beam • spring • mass • contact • rigid link • weighted link points A single point takes precedence over a feature of points or a pattern of points. A feature of points takes precedence over a pattern of points. Points take precedence over curves, edges, and surfaces. • beam • mass (in FEM mode) curves or edges An individual curve takes precedence over a composite curve. Curves and edges take precedence over surfaces. • shell • beam (surface-surface, in FEM mode) • mass (in FEM mode) surfaces A single surface takes precedence over a whole quilt.