Please, explain briefly but as clearly as possible the scope of the rights relating (exclusively) to the apartments and the ones relating to the building or to the communal elements owned jointly.
In the statutes of the building the co-owners describe what parts of the building are common and what parts of it are private. Simplifying, the building itself is common, and the apartments are private.
The common parts are co-owned by all the owners of the apartment and the apartment itself is the exclusive(single) property of the owner of that apartment.
The two kinds of parts are brought together in what is called the unit: each unit contains the apartment and a share in the common parts (expressed as a fraction of all the common parts, e.g. a 2 500/10 000 share). In this way the single ownership of the apartment is unbreakably linked to the co-ownership of the common parts of the building: forced co-ownership indeed.
There remains one last step: the contents of the rights. This is described in the regulation of co-ownership. Simplified, the apartment can be exclusively used and enjoyed by the owner (he/she can more or less do what he/she wants). The use of the common parts, on the other hand, is much more restricted: the details are spelled out in the regulation of co-ownership.
The regulation of co-ownership provides also the annual cost of the use of the common parts (maintenance, common electricity and heating, …). Normally, the share in these common costs follow the share in the common parts.
The statutes of the building and the regulation of co-ownership must be an authentic (notarial) act.