A single queue that manages and schedules OpenCL Commands in a OpenCL Context. Command queues are unique to a given OpenCL Context.
Example
Context (the workspace)
├── Device 1 (GPU)
│ ├── Command Queue A → [copy data, run kernel, copy results]
│ └── Command Queue B → [different operations...]
├── Device 2 (CPU)
│ └── Command Queue C → [other operations...]
└── Shared Memory Objects (visible to all devices in context)