Model checking is applied for verification of concurrent systems by users having different skills and background. This ranges from researchers with detailed knowledge of the inner workings of the tools to engineers that are mostly interested in applying the technology as a black-box. This paper proposes JoSEL, a graphical language for specification of executable model checking jobs. JoSEL makes it possible to work at different levels of abstraction when interacting with the underlying components of a model checking tool and thereby supports the different kinds of users in a uniform manner. A verification job in JoSEL consists of tasks, ports, and connections describing the models to verify, the behavioural properties to checked, and the model checking techniques to apply. A job can then be mapped onto components of an underlying model checking tool for execution. We introduce the syntax of JoSEL, define its semantics, and show how JoSEL has been used as a basis for the user interface of the ASAP model checking platform.