The L06 warp model is the same as the López-Corredoira et al. (2002) model, except for a $\phi _W$ of $+5^\circ$ and an extrapolated $z_W(13\ {\rm kpc}<R<16\ {\rm kpc})=z_W(13\ {\rm kpc})$ for the southern warp.

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They take constant height at R>14 kpc instead of R>13 kpc, and $\phi _W=-5^\circ$ instead of $\phi _W=+5^\circ$ . These parameters, however, do not affect the present comments.

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... populations

The small number of detected RR Lyrae stars in the CMa over-density can be accounted for by the halo and thick disc RR Lyrae population (Mateu et al. 2007).

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