Every device responds to the capability, status, and info commands. These commands obtain information about the device. For example, your application can determine if a videodisc requires a device element by using the command “capability videodisc compound file.” (This example returns false.) The flags listed for the required and basic commands provide a minimum amount of information about a device. Many devices supplement the required and basic flags with extended flags to provide additional information about the device.
When you request information with the capability, status, or info command, the argument list can contain only one flag requesting information. The string interface can only return one string or value in response to a command requesting information.