An empirical relationship is discovered for RS CVn type close binary systems between their absolute luminosity, L(MgII), of the ultraviolet magnesium doublet 2800 MgII, and the inter-component distance a of the system. It has the following form: L(MgII) similar to a(n) (Figure 1). It is shown that for the overwhelming majority of binary systems n = 1 (Figure 4). This correlation presents itself as a direct confirmation of the intercomponent origin of the observed emission, particularly, in the magnesium doublet in close binary systems. The basic relationship of intercomponent emission is derived in the form : L(MgII) = 1.0 x 10(32) a ergs s(-1). At the same time, accidental statistical divergences from this correlation are possible on both sides: as n > 1 as well n < 1 (Figure 4). The correlation n = 1 determines also the character, - i.e. cylindric for a stream - of the transfer of gaseous matter from one component of the system to the other, and in the general gas dynamics of the intercomponent medium. The existence of a new category of stellar atmosphere, - which we call roundchrom, is predicted, representing the common chromosphere of a superclose binary system, surrounding or blending both components of the system (Figure 3). The boundaries between the three most important divisions of magnesium doublet emission - chromosphere of single stars, roundchrom of superclose binary systems and intercomponent space - are established for RS CVn type systems. Finally, a number of new problems, both observational and theoretical, are brought forward.