This states whether this drive model supports self-encrypting-drive security, per the DriveSecCap isSupported property. This is the concrete gate an admin checks before assuming a data-at-rest encryption policy can actually be enforced on drives of this model — a drive whose capability record shows unsupported cannot participate in SED-based encryption no matter how the storage profile is configured. isSupported reading false for an older SAS drive model explains why applying a full-disk-encryption storage policy to a server with that drive fails or silently has no effect on that particular disk.