Value of Employee Approval limit is coming from Spending Limit in Purchase order workflow

Hi All,

Purchase order workflow has a condition when assigned to Managerial Hierarchy 

The value for Employee.Approval Limit.Purchase order is coming from the signing limit spending amount rather than Approval amount. Where is the limit value actually calculated ?It does not seem to be coming from "purchtabledocument"  class nor from "WorkflowLimitHierarchyProvider". Any pointers/directions would be appreciated

Thanks