1. A computing device-implemented method comprising: assigning, using a processing device, a first value to a resettable variable, the resettable variable being in a selected part of an executable state diagram model; setting the resettable variable to a second value during an invocation of the selected part of the executable state diagram model, the setting occurring after the assigning, and the setting performed using the processing device; and automatically resetting the resettable variable to a preset value before or during a subsequent invocation of the selected part of the executable state diagram model, the resetting including: resetting a value of the resettable variable after the selected part of the executable state diagram model is awakened but before the resettable variable is accessed in the selected part of the executable state diagram model.