Final answer:
The restriction with the MT number on the takeoff performance data refers to the maximum takeoff weight that an aircraft can safely operate at.
Step-by-step explanation:
The restriction with the MT number on the takeoff performance data refers to the maximum takeoff weight that an aircraft can safely operate at. This restriction is based on various factors such as runway length, ambient temperature, and altitude. For example, if an aircraft has a MT number of 150, it means it is limited to a maximum takeoff weight of 150,000 pounds.