auxiliary classes; may contain either a vector or NULL, [or a matrix, or an array, respectively], cf. J. Chambers, "green book".
these classes are all virtual: No objects may be created from it.
No methods defined with classs "vectororNULL", "MatrixorNULLorVector", and
"ArrayorNULLorVectororDataframeorSeqDataFrames" in the signature.
However, the generating function Dataclass dispatches according to
"DataframeorSeqDataFrames" or "ArrayorNULLorVector".
Thomas Stabla statho3@web.de,
Florian Camphausen fcampi@gmx.de,
Peter Ruckdeschel peter.ruckdeschel@uni-oldenburg.de,
Matthias Kohl Matthias.Kohl@stamats.de
Dataclass-class