A job may be regarded as temporary if it is understood by both employer and the employee that the termination of the job is determined by objective conditions such as reaching a certain date, completion of an assignment or return of another employee who has been temporarily replaced. In the case of a work contract of limited duration the condition for its termination is generally mentioned in the contract. To be included in these groups are: a) persons with a seasonal job, b) persons engaged by an employment agency or business and hired out to a third party for the carrying out of a "work mission" (unless there is a work contract of unlimited duration with the employment agency or business), c) persons with specific training contracts. If there exists no objective criterion for the termination of a job or work contract these should be regarded as permanent or of unlimited duration. This question is addressed only to employees. In the majority of the European Union countries most jobs are based on written work contracts. However in some countries such contracts exist only for specific cases (for example in the public sector, for apprentices, or for other persons undergoing some formal training within an enterprise). Taking account of these different institutional arrangements the notions "temporary job" and "work contract of limited duration" (likewise "permanent job" and "work contract of unlimited duration") describe situations which under different institutional frameworks, can be regarded as similar.