This work is devoted to the presentation of the experimental data describing the peculiarities of X-ray quasimonochromatic flux transportation by planar extended slit clearance at the slit width variation from 30 nm to 120 µm. The experimental data allowed to suppose the existence of a new mechanism for the X-ray flux propagation through extended slits with nanosize width. The model of the mechanism described briefly is founded on the concept of formation of a uniform interference field of X-ray standing wave in all space of the slit clearance. The planar X-ray waveguide-resonator (PXWR) was built based on the concept, and it demonstrated a set of original properties and peculiarities creating the background for the real nanophotonics. Some attention is drawn to the description of PXWR design perfection development.