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      <title>Tracking Mechanisms</title>
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      <div class="title_topic2" id="xps10_pagetitle">Tracking Mechanisms </div>
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      <p class="para_topic">Interoperability files contain associativity and tracking information that translator files such as IGES files don't. For example, if you import an IGES file into I-deas, the history tree node for the imported part is labeled as an &quot;orphan&quot; node. The term orphan means that no history is preserved to edit this feature. If a later IGES file is written, you will receive no automatic notification that the orphan node is out-of-date. There is also no association to tell you which orphan node the new IGES file should replace. Surfaces of the new IGES file do not necessarily use the same internal topological identification. When you replace the orphan feature with the newer IGES file, later added features are not tracked to surfaces and edges from the original part. Interoperability uses tracking mechanisms to solve these problems.</p>
      <p class="para_topic">The interoperability feature in the history tree in I-deas stores the NX or Parasolid filename associated to the feature so that it can check for changes to this file.</p>
      <p class="para_topic">The out-of-date notification method in I-deas is to check the date and time stamp on the NX part or Parasolid file. If this file is renamed, moved or restored, this mechanism may not give a true indication of an out-of-date part.</p>
      <p class="para_topic">When you open an exchange file or import a part from I-deas TDM in NX, the resulting NX part file records unique identifiers for the associated I-deas part to ensure that a subsequent update is for a different version of the same I-deas part. Because of this unique identifier, the part can be updated by reloading using either mechanism (a package file or from TDM) regardless of which way the part was originally imported.</p>
      <p class="para_topic">The exchange package file also contains other diagnostic information such as computed mass properties that can be used to check the accuracy of the transferred geometry.</p>
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