This term further distinguishes existing terms (-E3, +E9). It is an obvious parallel to dynamic valid-time grouping (+E1). Static is an appropriate term because the grouping intervals are determined from extrinsic information. The grouping intervals would not change if the information in the database changed.
Computing the maximum salary of employees during each month is an example which requires using static valid-time grouping. To compute this information, first divide the time-line into valid-time elements where each element represents a separate month on, say, the Gregorian calendar. Then, find the tuples valid over each valid-time element, and compute the maximum aggregate over the members of each set.