[Al Skierkiewicz]

Martin,
The language is the same as in previous years. The frame perimeter includes the bolts and whatever else may be sticking out of the robot frame. It is this size that is determined to be within the robot sizing parameters when in the box. The rules for pockets in the bumpers is the same as well. It allows teams to make small holes in the back of the bumpers to accommodate secure mounting of the bumpers to the robot frame without the added clearance provided by fasteners.

The full definition is this..
FRAME PERIMETER – the polygon defined by the outer-most set of exterior vertices on the ROBOT (without the BUMPERS attached) that are within the BUMPER ZONE. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE - the string describes this polygon.
As further explained here...
<R16> During normal operation no part of the ROBOT shall extend outside the vertical projection of the FRAME PERIMETER, except as permitted by Rule <G30>.
Note: This means no “mushroom-bots.” If a ROBOT is designed as intended, in normal operation you should be able to push the ROBOT (with BUMPERS removed) up against a vertical wall, and the FRAME PERIMETER will be the only point of contact with the wall.

Therefore as I interpret the sum of rules, the bolt heads that are in the bumper zone define the frame perimeter and any other projections outside the bumper zone cannot extend beyond those set by the frame perimeter except as applied in <G30>.
Hope this helps.