Thanks michelle, I finally found this parameter in our dictionnary 🙂 there is a T200 for LapD management, and others T200 for LapDm management.
Supervision of acknowledgements for SDCCH SAPI 0. = 220ms
Supervision of acknowledgements for SDCCH SAPI 3. = 450ms
Supervision of acknowledgements on RSL for OMU SW. = 1sec
and so on ….