Phase diagram of H₂O split into the seven regions listed in Table 1. Most region boundaries (solid lines) follow phase transition curves. The dashed lines are phase transitions that are not region boundaries, meaning the same EoS is used along the phase transition. The shaded areas show where neighbouring regions have to be interpolated. Region 7, where the EoS of Mazevet et al. (2019) is used, expands to temperatures up to 10⁵ K.