The data pointed to by this entry forms the initial part of a single RU. Subsequent entries in this group can add data to the RU. If this entry is encountered while in split or accumulate state, the previous buffer group is ended and the RUs from the data in that group are completed and sent; accumulate state is then entered. If a (1,0) entry is encountered in reset state, accumulate state is entered and no RU is sent at this time.