Abstract. With the use of a multi-machine pedestal database, essential issues for each regime of ELM types are investigated. They include (i) understanding and prediction of pedestal pressure during Type I-ELMs which is a reference operation mode of a future tokamak reactor, (ii) identification of the operation regime of Type-II ELMs which have small ELM amplitude with good confinement characteristics, (iii) identification of upper stability boundary of Type-III ELMs for access to the higher confinement regimes with Type-I or -II ELMs, (iv) relation between core confinement and pedestal temperature in conjunction with the confinement degradation in high density discharges. Scaling and model-based approaches for expressing pedestal pressure are shown to roughly scale the experimental data equally well and initial predictions for a future reactor case could be performed by them. It is identified that q and are important parameters to obtain the Type-II ELM regime. A theoretical model of Type-III ELMs is shown to reproduce the upper stability boundary reasonably well. It is shown that there exists a critical pedestal temperature, below which the core confinement starts to degrade.