Does anyone know of a way that I can check to see if my workbook has been
altered before it's closed?

I need to do this because I have a workbook where users record serial
numbers allocated to components, but sometime they look up the next number
and then forget to update the workbook with the numbers allocated, the result
being that the next person uses the same numbers again.

I'd like to create some sort of warning box if the workbook has been opened
but no updates have been made.

Not sure if this is possible, but I'd appreciate any ideas anyone lse may have

Thanks

Neil