+/* Causes the original contents of column "%(c)s" in 'row' to be
+ * verified as a prerequisite to completing the transaction. That is, if
+ * "%(c)s" in 'row' changed (or if 'row' was deleted) between the
+ * time that the IDL originally read its contents and the time that the
+ * transaction commits, then the transaction aborts and ovsdb_idl_txn_commit()
+ * returns TXN_AGAIN_WAIT or TXN_AGAIN_NOW (depending on whether the database
+ * change has already been received).
+ *
+ * The intention is that, to ensure that no transaction commits based on dirty
+ * reads, an application should call this function any time "%(c)s" is
+ * read as part of a read-modify-write operation.
+ *
+ * In some cases this function reduces to a no-op, because the current value
+ * of "%(c)s" is already known:
+ *
+ * - If 'row' is a row created by the current transaction (returned by
+ * %(s)s_insert()).
+ *
+ * - If "%(c)s" has already been modified (with
+ * %(s)s_set_%(c)s()) within the current transaction.
+ *
+ * Because of the latter property, always call this function *before*
+ * %(s)s_set_%(c)s() for a given read-modify-write.
+ *
+ * The caller must have started a transaction with ovsdb_idl_txn_create(). */