Teamcenter Unified Architecture - Important Terms

Occurrence :

  The same part may appear several times in the structure, but each occurrence of the part is unique (called the instance).

For example, the occurrence of the left front wheel of a vehicle differs from the occurrence of the right front wheel, even though the actual wheels are identical.

Its a relationship between the immediate parent assembly and its child component item (in an imprecise assembly) or item revision (in a precise assembly)

This is also called relative occurrence

Absolute Occurrence :

A BOM line represents an absolute occurrence with respect to the current top line in the product structure