Anne of Brittany writes to her husband Louis XII of France, at a desk supported by two trestles, each with two legs joined by a pinned halved joint. The trestles may be joined beneath the cloth, so as to be wide enough not to tip.
Louis XII of France writes back, from a similar desk, supported by two three-legged trestles, which may be free-standing. Both illustrations early 1500s.
There are two kinds of trestle desk: as with trestle tables, some have trestles joined by one or more stretchers (and sometimes to the desktop), and some have free-standing trestles. They can be dismantled, with the desk top removed from the trestles, for storage or transport.