L = isLocked(OBJ)
L = isLocked(OBJ) returns a logical value, L, which indicates whether input attributes and nontunable properties are locked for the System object, OBJ. The object performs an internal initialization the first time the step method is executed. This initialization locks nontunable properties and input specifications, such as dimensions, complexity, and data type of the input data. After the System object is locked, the isLocked method returns a true value.