Two phases of Android "back" key "up" and "down"

Hi everyone, the solar 2d documentation maybe have forgotten to include the two phases of Android “back” key, I just want to ask the difference between “down” phase and an “up” phase of an Android “back” key. Which one must be use, … etc… etc… Thank you very much

“down” is when the user presses the key, “up” is when the release it.

Thank you very much. May I know how or where did you find out? because I did not see this in the solar2d documentation. Thank you very much again Glitch_Games.

This is all detailed quite extensively in the documentation:

Thank you so much.