Defining the notion of order statistics for a multivariate sample is not obvious and can be done in many ways. In this talk  we consider a multivariate sample ordered according to an increasing family of conditional quantile surfaces, called isobar surfaces. We investigate histogram-type estimators of these isobar surfaces and we establish the asymptotic normality of these estimators. We study also  the uniform  a.s. consistency of these estimators, under some regularity conditions.