The BACnet Multistate Value (MSV), Multistate Input (MSI) and Multistate Output (MSO) objects encode enumerations with several states (3 or more discrete values), such as HVAC modes (Comfort/Standby/Eco) or system states (Auto/Manual/Off).

The split between Binary and Multistate is conceptual: Binary objects (BV, BI, BO) carry 2 states (on/off, true/false), whereas Multistate objects (MSV, MSI, MSO) carry 3 or more enumerated states. A typical MSV represents an HVAC mode such as {Comfort, Standby, Economy, Building Protection} coded as 1, 2, 3, 4, with the State_Text array supplying the human-readable labels. This avoids ad-hoc conventions on AV (e.g. 1=on, 2=off, 3=auto with hidden meanings) and keeps the BMS UI consistent across vendors.

Always populate the State_Text array: a Multistate object without labels is just a number on the wire and forces every operator to remember the mapping by heart.