An apparatus comprising: data sending circuitry to send data to a recipient over an interconnect; and determining circuitry to determine whether a portion of data to be sent by the data sending circuitry has a predetermined value; in which: in response to the determining circuitry determining that the portion of data has the predetermined value, the data sending circuitry is configured to perform data elision to: omit sending at least one data FLIT corresponding to the portion of data having the predetermined value; and send a data-elision-specifying FLIT specifying data-elision information indicating to the recipient that sending of the at least one data FLIT has been omitted and that the recipient can proceed assuming the portion of data has the predetermined value, where said data-elision-specifying FLIT is a FLIT other than a write request FLIT for initiating a memory write transaction sequence; wherein the data-elision information is specified using fewer bits than the omitted at least one data FLIT. data sending circuitry to send data to a recipient over an interconnect; and determining circuitry to determine whether a portion of data to be sent by the data sending circuitry has a predetermined value; in which: in response to the determining circuitry determining that the portion of data has the predetermined value, the data sending circuitry is configured to perform data elision to: omit sending at least one data FLIT corresponding to the portion of data having the predetermined value; and send a data-elision-specifying FLIT specifying data-elision information indicating to the recipient that sending of the at least one data FLIT has been omitted and that the recipient can proceed assuming the portion of data has the predetermined value, where said data-elision-specifying FLIT is a FLIT other than a write request FLIT for initiating a memory write transaction sequence; wherein the data-elision information is specified using fewer bits than the omitted at least one data FLIT. in response to the determining circuitry determining that the portion of data has the predetermined value, the data sending circuitry is configured to perform data elision to: omit sending at least one data FLIT corresponding to the portion of data having the predetermined value; and send a data-elision-specifying FLIT specifying data-elision information indicating to the recipient that sending of the at least one data FLIT has been omitted and that the recipient can proceed assuming the portion of data has the predetermined value, where said data-elision-specifying FLIT is a FLIT other than a write request FLIT for initiating a memory write transaction sequence; omit sending at least one data FLIT corresponding to the portion of data having the predetermined value; and send a data-elision-specifying FLIT specifying data-elision information indicating to the recipient that sending of the at least one data FLIT has been omitted and that the recipient can proceed assuming the portion of data has the predetermined value, where said data-elision-specifying FLIT is a FLIT other than a write request FLIT for initiating a memory write transaction sequence; wherein the data-elision information is specified using fewer bits than the omitted at least one data FLIT.