The number of counts indicates how many values can be shown in the display. Usually the display is four-digit, as on this device, meaning that as a rule the first digit will only be either 0 or 1. This means the device can display a range from 0000 to 1,999, or 2,000 count values, with the decimal point at any position. Because the measurement range is always linked to the count range on measurement instruments with numeric displays, this also determines the resolution of the measured value. A digital multimeter with 2,000 counts, for example, has a resolution of 10 mV in a 20 V measuring range.

TRMS is an abbreviation of 'True Root Mean Square'. A multimeter without TRMS can only accurately display the root mean square of sinusoidal voltage. If a non-sinusoidal voltage is measured, the RMS value of the voltage is not correct.

CAT I applies to measurements on circuits that have no direct connection to the mains (e.g., battery operated). CAT II applies to measurements on circuits with a direct connection to the mains (e.g., household devices). CAT III applies to measurements within the building installation (e.g., distribution boards, wiring, outlets or switches). These measurements are only permitted behind the electricity meter! CAT IV applies to measurements at the source of low-voltage installations (e.g., meters, main connection, primary overcurrent protection). These measurements are also permitted before the electricity meter.