Sorry, that was typo; I meant Shift+M, the shortcut for Set Measure/Beat At Now. Yes, if the the new tempo is 133BPM, and the first set point was 2:01:000, you would set the Now time at Measure 135, Shift+M, and enter the tempo you want to get back to plus 2 measures. Suppose that target tempo is 100. What you're doing is telling SONAR to change the tempo at 2:01:000 to make 100 measures go by in the time of 133, counting from measure 2. This is the same having 100 beats go by in the time of 133; it's just easier to work with full measures.