occurs in has quality marine tidal flow process semi-diurnal marine tidal flow zone semi-diurnal marine tidal flow process envoMarine envoCmecs semi-diurnal tidal flow A marine tidal flow process which occurs twice per day, resulting in two high and two low tides per day, both of roughly equal amplitude. This class broadly aligns to the Coastal and Marine Ecological Classification Standard (CMECS). This class is provided as the processual equivalent of CMECS unit 666 "Semi-diurnal Tidal Flow" (https://cmecscatalog.org/cmecs/classification/unit/666.html); however, based on its definition, CMECS:666 is more accurately mapped to ENVO:01001340 as the definition aligns with ENVO's "environmental zone" semantics. A class has been created to accommodate the semantics of the resulting hydroform (ENVO:01001336). Please consult the CMECS catalogue (https://cmecscatalog.org/) for authoritative and semantically unconstrained definitions. discontinuous