With this record you can set the number of CPUs you want to use (nproc). If your TOCHNOG implementation does not allow for more processors, this record is ignored. In fact, not the number of processors but the number of threads is set (that is, if you use 2 threads while your system only supports 1 processor than those threads are split over that single processor).
You can also set an environment symbol TOCHNOG_OPTIONS_PROCESSORS to nproc. In this way, you do not need to set the number of processors in each input file separately.
Error messages may become confusing when you use more than one processor.
Default nproc is 1.