Op versus OpDefault
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<img src="/wiki/images/6/64/Op.png" alt="op" width="400" height="308" />
OpDefault is configured with sytem privileges and is used when when system manager logs in as pwrp and print 'rt_xtt' in a terminal window with.
Op should be used when an operator logs in with operator privileges. In this case rt_xtt is inserted as an startup application with the opplace object as an argument to rt_xtt.