Use the values of this type primarily for these purposes:
As members of the StaplingCapability collection, which is a property of PrintCapabilities, these values indicate the types of stapling that a printer supports.
As the value of the Stapling property of a PrintTicket, the value instructs the printer whether, and where, to staple.
The Unknown value is never used in properties of PrintCapabilities objects.
You should never set a PrintTicket property to Unknown. If some other PrintTicket producing application has created a PrintTicket document that sets the stapling feature to an unrecognized option (that is, an option that is not defined in the Print Schema), then a PrintTicket object in your application that is constructed with that document will have Unknown as the value of the Stapling property.
Although the PrintTicket and PrintCapabilities classes cannot be inherited, you can extend the Print Schema to recognize print device features that are not accounted for in the PrintTicket or PrintCapabilities classes. For more information see How to: Extend the Print Schema and Create New Print System Classes.