A set of DF-objects related to the same system is represented by so called [DFset]DFset-object. For example, a single *.rdf-file corresponds to a DFset. It shall not be mixed with list of DF-objects (DFs list), such as [DF1, DF2, ... DF_N], as in such list DFs are not necessary related to the same system.
The most complex structure is a list of DFset-objects, which is generally used for comparison/plotting of DFsets, such as comparing set of the reference RDFs with set of RDFs sampled in the IMC. Typical example of DFset-list is a list of RDFs sampled at different iterations of IMC.