In embodiments, a transmitting device sends a time reference field to a receiving device when indicating that no more frames will be sent to the receiving device. The time reference informs the receiving device of the length of time that the transmitting device has committed not to transmit to the receiving device. When operating in conformance with the ECMA-368 standard, the time reference allows the transmitting device to control the length of the commitment period after the MORE FRAMES bit is set to zero. In this way, the commitment not to transmit may be made for a shorter time than the time until the beginning of the following Distributed Reservation Protocol (DRP) reservation block or the time to the beginning of the following superframe. The time reference may be added in the Medium Access Control header or included in a vendor-specific message, for example.