Morkus from Orkus
From the 1e DMG page 110.Never played 1e AD&D either. Though I thought rolling under stat was the general resolution mechanics for the game?
"There will be times in which the rules do not cover a specific action that a player will attempt. In such situations, instead of being forced to make a decision, take the option to allow the dice to control the situation. This can the player dice to see if he or she can make that percentage. You can weigh the dice in any way so as to give the advantage to either the player or the non-player character, whichever seems more correct and logical to you while being fair to bath sides. be done by assigning reasonable probability to an event and then letting."
In WotC terms it essentially says to come up with a DC and let the player roll.