This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in cyclic amidines. The systematic name of this enzyme class is 5,10-methenyltetrahydromethanopterin 10-hydrolase (decyclizing). Other names in common use include 5,10-methenyltetrahydromethanopterin cyclohydrolase, N5,N10-methenyltetrahydromethanopterin cyclohydrolase, and methenyl-H4MPT cyclohydrolase. This enzyme participates in folate biosynthesis.