search through the used scripts for skill1, to see whether it is already used for another purpose.

Most probably the door uses something from other places in the wdls of the templates: look for defines, skills flags and variables which are used in the function. Beside that the door function uses an event. An event, in this case probably a scan event, reacts when f.i. two entities come near to each other, in this case the player to the door. This means in the player action must be something like enable_scan. Look into the manual for event.
Another possibility is, that there is an id for the event to make a difference between an event where a granate explodes near the player or the player pushes a button in game or he comes near a door, because otherwise the player could loose health, because of coming near the door or such...