For each mask in a group, TISM supports 2 TCL scripts.
Script 1 - On the fly execution
This script is executed on the fly, before the message is sent.
It can be used to transform message.
It is highly recommended to avoid to use this kind of script for heavy computation.
Script 2 - Parallel execution:
This script is executed in a separate thread.
The time execution is not known, but it doesn't block the system. Heavy computation must be done in this script.