Sometimes it makes sense to be able to move a button from one place to another – possibly change its use from function to decorative and then back to function again – and this is one way of giving a button roving status.
A sturdy linen yarn is threaded through the holes….
…. and knotted a few times on the back of the button.
Here it is attached to a vest by catching those knots in the back of the vest with that most wonderful of invention – the safety pin.
Purely decorative, this 'button by Bob' goes traveling on a hat.
The pinned side.