All of the specification limits and net content limits are optional; however, if you do not specify the limits then Real-Time SPC cannot calculate capability metrics or % out-of-specification.
Because T1 and T2 setpoints work together, if you specify one of them, you must specify both. Lower T2 must be less than Lower T1 and Upper T2 must be greater than Upper T1.
For more information on limits, go to Specification limits and Net content limits.