This is the master enable/disable switch for whether the plant's entire time-of-day load-shed schedule - all 21 per-day, per-bank disconnect and reconnect setpoints in this MIB - is actually active, per the description. Because every one of those individually configured Sunday-through-Saturday schedule entries for all three load banks only takes effect while this flag is enabled(1), an admin who has carefully configured a shed schedule but leaves this set to disabled(2) will find none of it actually running. A value of 1 means the configured weekly schedules for banks 1, 2, and 3 are all actively executing; setting it to 2 suspends all of them without erasing the configured times.