Sidechain Operator Nodes - SONs facilitate the transfer of off-chain assets (like Bitcoin, Hive, or Ethereum tokens) between the Peerplays chain and the asset's native chain. These nodes often run the Peerplays node software and node software of other chains.
The software used to run Witness, API (full), Seed, and SON nodes is named witness_node. All these node types are run with the same software. What makes these nodes different is how that software is configured and how it's used.
SONs will also require the use of software supplied by other chains, like Bitcoin Core for example.
BOS nodes use a collection of software known as the Bookie Oracle Suite.