http://marklogic.com/xdmp/privileges/xdmp-transaction-complete
Use this function to explicitly roll back a remote transaction running in
"update" or "query" transaction mode. See
xdmp:rollback for more information.
Any statement executing under the remote transaction is halted immediately.
If the named host or transaction does not exist, an error is raised.
xdmp.transactionRollback(xdmp.host("some-host.yourdomain.com"), some-txn-id);
=> Empty. The given transaction is rolled back and all
modifications made by the transaction are discarded.