Here are the workflow status codes which are required, for example, you want to filter a view on the workflow status. The status enumeration is defined by the SPWorkFlowStatus enum, within the Microsoft.SharePoint.Workflow namespace in the Microsoft.SharePoint assembly.
In case if you are retrieving the list values in a SQL Reports using the SharePoint provided web service you will get these status codes only and not the text values.
NotStarted = 0
FailedOnStart = 1
InProgress = 2
ErrorOccurred = 3
StoppedByUser = 4
Completed = 5
FailedOnStartRetrying = 6
ErrorOccurredRetrying = 7
ViewQueryOverflow = 8
Max = 15
In addition, if you are using the OOTB Approval workflow then the return codes for this, as defined in the ReviewRoutingState enumeration within the Microsoft.Office.Workflow namespace (Microsoft.Office.Workflow.Routing assembly), are:
Canceled = 15
Approved = 0×10 (16)
Rejected = 0×11 (17)






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