Does a signal called "EN" stand for something special in this circuit?

[zenterix]

Homework Statement

Write a boolean expression that describes the function of the circuit below.

Relevant Equations

My question is what does "EN" stand for in the circuit?

If it is simply a signal like A, B, and C then the function represented by this circuit is ##\bar{(AB+C)EN}##.

 

[.Scott]

Perhaps "enable".