How to recognixe termchar was entered

Hi Everyone
I am looking for the equivalent functionality of a record field.termchar shadow variable in a regular field.
The vxml script collects dtmf digits and needs to know whether the termchar was entered. The digit collection stops when the termchar is entered or when one of the timeout or length condns is met, is there a way of finding out whether the termchar was entered.
In the record field you can do this with the termchar shadow variable. I'm looking for this in a regular dtmf field.

Thanks
gowthami