[Math] Key The availability of Math soft keys varies by measurement function. [Display] Key [Utility] Key Soft keys Description Null Enable/disable use of null values and specify null value to use. dB / dBm Configure dB，dBm. Statistical information Enable, disable, and clear statistics. Limiting value Enables or disables upper and lower limits. Soft keys Description Display Choose what to display: number, bar meter, histogram, or trend chart. Label Enables or disables display messages. Label Text Edit the text displayed when the soft key LABEL is on. 2nd Meas Choose auxiliary measurement Digit Mask Set the number of digits displayed in the measurement.