  In this paper, the concept of Musielak N-functions and Musielak-Orlicz spaces
generated by them well be introduced. Facts and results of the measure theory
will be applied to consider properties, calculus and basic approximation of
Musielak N-functions and their Musielak-Orlicz spaces. Finally, the
relationship between Musielak N-functions and Musielak-Orlicz functions and
thier Musielak-Orlicz spaces will be considered using facts and results of the
measure theory too
