contains process semi-diurnal marine tidal flow zone This class aligns to the Coastal and Marine Ecological Classification Standard (CMECS). In ENVO, we may adapt the definition for consistency, but the semantics (meaning) of the term should be unaffected. In this case, the definition aligns with ENVO's "environmental zone" semantics. Alternate classes have been created to accommodate the process of diurnal tidal flow. The as the frequency of the process does not influence the semantics of the resulting hydroform, please use ENVO:01001336 to reference the hydroform rather than the zone or the process. Please consult the CMECS catalogue (https://cmecscatalog.org/) for authoritative and semantically unconstrained definitions. CMECS:666 semi-diurnal tidal flow A marine tidal flow zone in which ocean waters undergo a semi-diurnal (twice per day) tidal oscillation - with two high and two low tides per day of roughly equal amplitude. envoMarine envoCmecs https://cmecscatalog.org/cmecs/classification/unit/666.html marine tidal flow zone semi-diurnal marine tidal flow process