Quark-mass dependence of structure functions for deep-inelastic scattering

It is shown that, in the current-fragmentation region, the difference of the structure functions for deep-inelastic scattering with and without heavy-quark production that are calculated at a given small value of X-Bj scales at high Q(2). A lower bound on the charmed-quark contribution F-2(c)(Q(2),x) to the total structure function is found and compared with data recently obtained by the H1 collaboration for F-2(c)(Q(2),x).