On the boundary between contract and property law: real burdens

The legal systems described adhere to the rule that servitudes cannot contain a burden to do something. Most systems allow that a main duty to tolerate, or not to do, is extended with a positive duty in support of the main negative duty. Dutch law even allows positive obligations as the only contents of a servitude, but these are restricted to maintenance works. Scots law goes a step further by allowing affirmative real burdens. German law also allows positive real burdens in the form of the Reallast. German and Dutch law also allow contractual clauses that seek to overcome the restriction in the law of servitudes by imposing a positive duty on a certain performance and the additional duty to pass the duty on to a subsequent owner of the land.