An E region was a region of the ionosphere.
In 2368, Data told William T. Riker that the Magellan had reached the E region of El-Adrel IV's ionosphere. (TNG: "Darmok")
Memory Alpha
An E region was a region of the ionosphere.
In 2368, Data told William T. Riker that the Magellan had reached the E region of El-Adrel IV's ionosphere. (TNG: "Darmok")