EMA C++ Performace Tools Guide : 4 Consumer Performance Tool : 4.3 Latency Measurement
 
4.3 Latency Measurement
Provider applications encode the timestamp as part of their message payload. The initial timestamp is taken at the start of encoding, and added as field TIM_TRK_1 (3902) in Update messages and TIM_TRK_3 (3904) in Generic messages. When this field is detected, the EmaCppConsPerf gets the current time and computes the difference to measure latency.
When configured to do so via appropriate command line parameters, the Consumer application will encode timestamps as part of Generic messages payload. The timestamp is taken at the start of encoding and stored in the field TIM_TRK_3 (3904). The Performance Provider application can detect this field and calculate the latency by subtracting the received value from the current timestamp.