This read-only integer, from 1 to 10, indexes a combined phase-and-bank load status table where all phase rows come before any bank rows. Admins use it to know whether a given row of load, voltage, and power data describes a phase or a bank, since the ordering convention determines that. On a three-phase PDU with two banks, indexes 1-3 describe the phases and indexes 4-5 describe the banks, so an admin must know the phase count to correctly interpret index 4.