Adapted from CIM data models. A value associated with a specific kind of limit. The sub class value attribute shall be positive. The sub class value attribute is inversely proportional to OperationalLimitType.acceptableDuration (acceptableDuration for short). A pair of value_x and acceptableDuration_x are related to each other as follows: if value_1 > value_2 > value_3 >… then acceptableDuration_1 < acceptableDuration_2 < acceptableDuration_3 < ... A value_x with direction='high' shall be greater than a value_y with direction='low'.