Version management in the ROOT file

In the ROOT file parameter containers are stored as objects. Every time an object is written it gets automatically a new version incrementing the former version by 1, starting with 1 in each newly created file. By default the Read() or Find() functions provided by ROOT read the object with the highest version. A retrieval of another version is possible by adding ";version number" to the name of the parameter container. The information 'which run corresponds to which version' of each parameter container must be stored in the ROOT file together with the data.