how to get current transport time?

From the SDK docs:
"An ITM-aware object can schedule events to occur when the transport
reaches a specific time, or find out the current transport state."

How to do that, find out the current transport state, i.e. the current
time of a linked transport?
I would like to have in my external more or less the same
functionality than what "when" does.

Any hint would be appreciated as I'm unable to find a solution in the
ITM API or the delay2 example.

Thanks,
Roby