  Constant dimension codes, with a prescribed minimum distance, have found
recently an application in network coding. All the codewords in such a code are
subspaces of $\F_q^n$ with a given dimension. A computer search for large
constant dimension codes is usually inefficient since the search space domain
is extremely large. Even so, we found that some constant dimension lexicodes
are larger than other known codes. We show how to make the computer search more
efficient. In this context we present a formula for the computation of the
distance between two subspaces, not necessarily of the same dimension.
