An item number is mandatory in our set-up, however this is not shown with a red asterix so users visually don't see it's mandatory and it's often skipped.
In addition, when the users leave it blank they don't get any notification and the requisitions goes to review or post control because item number is missing. It would be convenient if users get an error or warning before posting, as this would take away a lot of the errors and req's sent to post control.