Approver Order

Forgive me if the answer here may seem obvious, but I am just trying to understand the PO Approval table and wanted to know what the purpose of the "Approver Order" (3rd) column is in relation to the project in question?

dyla-82ab

Moderator note: Edited out personal information from the image.

It is in the event that you need two separate approvers for a particular project. For example a project needs approval from both the project manager and his/her manager as well.
If you go to the manager app and look under approvers you will see where that is editable.
Hope that helps. I new at this as well.