  We study the formal precision of the relative velocity lattice Boltzmann
schemes. They differ from the d'Humi\`eres schemes by their relaxation phase:
it occurs for a set of moments parametrized by a velocity field function of
space and time. We deal with the asymptotics of the relative velocity schemes
for one conservation law: the third order equivalent equation is exposed for an
arbitrary number of dimensions and velocities.
