Definition:QEF

Definition
The initials of Quod Erat Faciendum, which is for which was to be done.

These initials were traditionally added to the end of a geometric construction.

This is practically never seen nowadays outside translations of.

If there is a need for such an indication, the Halmos symbol $\blacksquare$ would be used instead.

does not bother to distinguish between use of QEF and the better-known QED, and recommends the use of the qed template exclusively instead.

Also known as
Some sources render it as Q.E.F. (that is, with dots).