When the TDS200 shows a letter R or T within a box what does this mean?

When the TDS200 shows a letter R or T within a box what does this mean?

When the scope's not triggered, R indicates it's ready. When it's triggering, a T is displayed. At 100mS/div and slower, and in Auto trigger, Scan will be displayed, indicating the scope is running in untriggered scan mode. When the timebase is stopped, a stop sign is displayed.