Performing TMS (Truth-Maintenance) on an assertion essentially asks the system to reevaluate all of the arguments for that assertion. This is most useful when the assertion has a deduced source which depends on an HL (Heuristic Level) support which no longer holds. Thus, if an assertion looks like it has a stale HL support justifying it, performing TMS on it will make the stale argument go away.
Choosing to perform full TMS on a constant involves performing TMS on every assertion involving the constant. Since this is potentially very time consuming (depending on the number of assertions involving the constant), this confirmation page appears as a precaution whenever the "Force TMS" link is selected in the Constant Index.
The text in the middle of the confirmation page lists both the constant on which TMS is to be performed, as well as the number of assertions that will be affected if TMS is done. If this number is somewhat small (e.g., under several hundred), the time involved will be trivial; however, a larger number of assertions (e.g., several thousand) will require more time to complete.
Press the [Do it!] button to force TMS on every assertion involving the given constant.
Press the [No] button to abort the TMS operation and return to the Constant Index.