UNIOP HMI panel

Hello All,
I've a UNIOP panel (EK-04) VER. 4.40,when i checked the plc status from its (SYSTEM) menu, the status says (PLC.......COMM ON 00) as shown in the attached image.
I've no problem with the panel and it is working correctly but i need to know the meaning of the no. (00) in that line !..
what does (00) referring to PLZ?..

The current communication status is displayed in the System Menu of the UniOP.

Communication status ON = OnLine. The number shows the code of the current communication error or the code of the last error encountered. When the error code 0 is shown, it means there have been no communication errors since system start-up.

Hope This Helps
Tom

Thank you wolverine1981,that is very suffecient details for me.