  We prove a first part of the standard description of groups $H$ lying between
an exterior power of an elementary group $\bigwedge^m E_n(R)$ and a general
linear group $GL_{n \choose m}(R)$ for a commutative ring $R$, $2\in R^*$ and
$n\geqslant 3m$. The description uses the classical notion of a level: for
every group $H$ we find a unique ideal $A$ of the ground ring $R$ which
describes $H$.
