New in 4.2
TIMING MARK is used by some hosts as a keepalive mechanism.
It is also useful for emulator unit testing, to synchronize data sent from the host to the emulator. E.g., a particular set of records is sent to the emulator for testing, followed by a TIMING MARK. The test can assume that when the emulator increments the result of Query(TimingMark), it has processed those records.
The return value is an integer.
x3270> Query(TimingMarks) 2
Added to x3270 4.2 in 2021.