ETE stands for Extra-Terrestrial Entities. After a crashed UFO was found in Roswell, and more and more reports of UFOs started coming in, the US Government made a list with the different types of visitors that had been encountered.
Initially, nine different types of aliens were identified. They were refered to as ETE-1, ETE-2 (The Eben, from Serpo), ETE-3 (The Greys), etc.
Even though the list is by now completely outdated, the ETE classifications are still classified.
This topic was copied from the HyperBase and is likely to be revised.