  Bezier parametric patches are used in engineering practice quite often,
especially in CAD/CAM systems oriented to mechanical design. In many cases
quadrilateral meshes are used for tessellation of parameters domain. We propose
a new modification of the Bezier cubic rectangular patch, the BS-patch, which
is based on the requirement that diagonal curves must be of degree 3 instead of
degree 6 as it is in the case of the Bezier patch. Theoretical derivation of
conditions is presented and some experimental results as well. The BS-Patch is
convenient for applications where for different tessellation of the u-v domain
different degrees of diagonal curves are not acceptable.
