Only thread domains associated with execute objects, i.e. objects implementing the execute interface, are listed by this command unless the -a flag is specified, in which case cell objects and thread domains associated with cells are also included in the output.
Thread domains are entities that can be simulated in parallel with other thread domains. The thread-domain partitioning is managed by device models but depends on the active threading mode used by the simulation, which can be changed with the set-threading-mode command.