In contrast to earlier releases, vSphere 5.0 introduces a two-level category and severity classification of patches and updates. ESXi 5.0 and later host patches have severity and category information included in the metadata, and the values for severity and category are reclassified.
ESX/ESXi 4.0 and earlier host patches have only severity information in the metadata, but not category information. Update Manager 5.0 and later translates metadata from the format for earlier patches to the reclassified format, so that earlier patches without category information are included in dynamic baselines correctly.
The Update Manager interface displays the severity and category for patches in the Patch Repository tab. You can use severity and category as criteria for the creation of dynamic patch baselines. Update Manager uses tags in bulletin.xml as the source for the value of severity and category of patches.