In the lists displayed in the Document View tab and in the Part View tab, each item is associated with two icons:
In addition, the items which haven't been previously saved into any project can be distinguished by a "spark" on the top-left-hand corner of the "floppy disk" icon. Components not bound to be saved in the archive (local components or X-Refs in local copy or read-only ones) don't have an associated "floppy disk" icon.
e-Learning on Assemblies and Mating