In the present paper, we prove the first part in the standard description of groups H lying between m E(n, R) and GL ( n m ) (R). We study the structure of the group m E(n, R) and its relative analogIn the considering case n 3m, the description is explained by the classical notion of level : for every such H we find unique ideal A of the ring R.Motivated by the problem, we prove the coincidence of the following groups: normalizer of m E(n, R), normalizer of m SLn(R), transporter of m E(n, R) into m SLn(R), and a group m GLn(R). This result mainly follows from the found explicit equations for the algebraic group scheme m GLn( ).