What does the 'Reference Number' column represent on the Import Template for Purchase requisition?

Reference_Number is a unique identifier for the import batch to group the Purchase Requisition lines together so it can be validated together. 

The Reference_Number should be consistent for the all of the records in the import so that they can then use that reference number to validate/import the records. 

This field is strictly for the importing process, it will not appear on the newly created records in Axiom.