This matter is not harmonised at the European level, and is therefore regulated by national laws. However, as a general principle in Europe, the rights to intellectual property developed by an employee in the course of his employment duties usually belong to the employer. Sometimes an assignment is mandatory, such as where employee works (inventions) are assigned by an employee to the employer because of the employment contract. On the other hand it is generally acknowledged that the rights to intellectual property (e.g. inventions) developed "on the side", with no relation to the employment relationship and without use of company resources, is the property of the employee.