A map is included to test the use of the keypad.
In the map there are three doors with keypads. Press on the keypad to bring it up. Use movement keys to navigate, Fire to enter the code and AltFire to quit.
The codes for the doors are (from left to right): 734, 931 and 579.
Spoiler: ScreenshotDownload: https://dl.dropboxusercontent.com/s/27p ... keypad.zip