  In this paper we propose a numerical scheme for partitioned systems of index
2 DAEs, such as those arising from nonholonomic mechanical problems and prove
the order of a certain class of Runge-Kutta methods we call of Lobatto-type.
The study of nonholonomic systems has recently shown a new interest in that
theory and also in its relation to the new developments in control theory,
subriemannian geometry, robotics, etc. The proofs and general outline of the
paper follow a similar procedure of the one by L.O. Jay in the non-partitioned
setting, but we tackle the issue of having two different sets of coefficients
in interaction.
