This is half of a tab to be copy/pasted into other PCB designs when creating panels of boards that require some spacing between them. Particularly useful when creating a panel of boards with parts that hang off the edge. Rather than butt boards together with a vscore, they boards can be held together with this long tab, allowing for space between boards, so that parts don't encroach on the neighboring board's space.
Below you can see 2 tabs used to hold this panel of 4 together, so the audio jack doesn't hang over onto the adjacent board--
The hardware is released under Creative Commons Share-alike 3.0.