Is there a more user friendly way to describe the 'Vacuum defs' function ?

How about we rename something like 'Document Cleanup' ?

Maybe even a dialog with checkboxes and explanations of the various options:

Cleanup and remove the following unused definitions from this document
* Unused gradients
* Unused color profiles
* Unused patterns
* Unused markers
* Unused scripts
* Unused clipping paths
* Unused filters etc