support both of these types.)
For a @var{type} of @code{'dbm}, there are no subtypes, so
-@var{subtype} should by @code{nil}.
+@var{subtype} should be @code{nil}.
For a @var{type} of @code{'berkeley_db}, the following subtypes are
available: @code{'hash}, @code{'btree}, and @code{'recno}. See the