The presumption also affects the types of services that the law recognizes. If easements are of a negative nature – where they limit the freedom of the owner in the occupation and use of his property – they belong to certain known categories. Since they constitute an anomaly in the law, because they restrict the freedom of the owners, the law is careful not to extend them beyond the known categories of the law. This is an issue when it comes to a restriction based on an explicit agreement or by agreement. Some elasticity in recognized categories may be allowed in such a case, since the owner has agreed to restrict his own freedom. But that`s another thing when you propose to acquire a prescription easement. If an easement prevented him from constructing a building that would disrupt these signals, he might not be able to build essential structures at all.