A fabric is a logical container for holding a group of devices. Here it denotes a collection of devices that are connected in a fabric topology and on which you can configure underlay and overlay.
For more information about the commands, see the ExtremeCloud Orchestrator Command Reference, 3.2.1
.Errors occurring on the device during fabric creation are tagged against the devices and can be retrieved from the CLI and REST APIs for use in taking corrective or remedial actions.