  We revisit the chiral transition in the finite density Sakai-Sugimoto model
and find that, at fixed temperature $T$, the magnetisation near the critical
line $\mu_c(B)$ acts as an order parameter to distinguish Inverse Magnetic
Catalysis from Magnetic Catalysis. Moreover, we propose a universal relation
between $\mu_c (B)$ and the magnetisation that allows us to predict the
behaviour of the former from the behaviour of the latter. We find that a
similar relation holds, at fixed chemical potential $\mu$, for the critical
line $T_c(B)$. Our results are obtained by investigating a fully numerical
solution to the relevant equations. At low temperatures our results reduce to
those obtained by Preis, Rebhan and Schmitt [JHEP 1103 (2011) 033], based on a
semi-analytic approximation.
