2013

When filtering is set for history subobjects, you can only select the wireframe
representations of portions of objects removed during a union, subtract, or
intersect operation.
Subobject Selection Filter Cursors
When a subobject selection filter is set, the following images are displayed
next to the cursor:
Vertex filtering is on
Edge filtering is on
Face filtering is on
History subobject filtering is on
1496 | Chapter 4 System Variables