 While I2C only arbitrates between masters, SMBus uses arbitration in three additional contexts, where multiple slaves respond to the master, and one gets its message through.PMBus version 1.3 extends the SMBus alert response protocol in its "zone read" protocol.Slaves may be grouped into "zones", and all slaves in a zone may be addressed to respond, with their responses masked (omitting unwanted information), inverted (so wanted information is sent as 0 bits, which win arbitration), or reordered (so the most significant information is sent first).