defined context set (OSI) (DCS)

The Defined Context Set(DCS) is a context described in the International Telecommunication Union( ITU) Recommendation X.216 for the delivery and use of presentation layer services.

The Presentation Layer is responsible for the reconciliation of the various Transfer Syntaxes with the Abstract Syntaxes by the application instances when they exchange their information at the Presentation Layer. The application instances must assume that the presentation layer supports the transfer syntax. The responding application instance thereby relies on corresponding presentation contexts, which are referred to as Defined Context Set (DCS).