  This article fills some gaps in Voevodsky's construction of the Steenrod
operations acting on the motivic cohomology with coefficients in Z/lZ of
motivic spaces in the sense of Morel and Voevodsky over a perfect field of
characteristic different from l. Moreover, as a consequence of the method of
proof of a theorem by Voevodsky on stable cohomology operations, we show that
the spectrum that represents motivic cohomology with coefficients Z/lZ has no
nonzero "superphantom" endomorphism.
