+.\"Three additional options may be specified by
+.\".IR or 'ing
+.\"them into the
+.\".I flags
+.\"argument.
+.\".TP
+.\"DB_LOCK
+.\"Do the necessary locking in the database to support concurrent access.
+.\"If concurrent access isn't needed or the database is read-only this
+.\"flag should not be set, as it tends to have an associated performance
+.\"penalty.
+.\".TP
+.\"DB_SHMEM
+.\"Place the underlying memory pool used by the database in shared
+.\"memory.
+.\"Necessary for concurrent access.
+.\".TP
+.\"DB_TXN
+.\"Support transactions in the database.
+.\"The DB_LOCK and DB_SHMEM flags must be set as well.