2.2.3.8 $T (Test Data Notification) Packet
The $T (Test Data Notification) packet is sent by the server in the response to the first in a series of two Pipeline requests (section 2.2.2.5).<58>
A $T packet is defined as a Framing header (section 2.2.3.1.1) with the following additional details:
B (1 bit): As specified in section 2.2.3.1.1.
Frame (7 bits): As specified in section 2.2.3.1.1.
PacketID (1 byte): This field MUST be set to the character "T" (0x54).
PacketLength (2 bytes): This field MUST be set to 0.
Reason (4 bytes): This field MUST NOT be present.