Clarifying Problems in the Description of Pre Main Sequence Evolution

We comment on a few points about modeling of pre main sequence (PMS) evolution, and try to derive some constraints on the stellar evolution during this phase, in spite of the parametric description of convection. We discuss: i : the role of deuterium burning and the choice of the initial starting model, ii : the results of models in which convection is calibrated using the 2D RHD simulation; iii : lithium burning and HR diagram location in the models calibrated -or not- on the solar radius. We stress that PMS binaries and lithium depletion in young clusters both point toward very inefficient convection in PMS, and that this result does not seem to be due to the use of local convection models.