I apologize for confusing you.
I meant to point out that tieing validation to leaving text fields can develop into nasty logic trees. Such as the example I presented here:
And I was off thinking nasty thoughts of:
1) Fill in Engineer 1
2) Fill in Engineer 2
3) Blank out Engineer 1
4) Commit the changes
Validation on the AfterUpdate event of each field could not comprehend what one of a bazillion possible ways the user wishes to proceed through the controls. "Entered data into the wrong controls, so user wishes to copy/paste shift the data to the correct controls" comes to mind.
Validating all of the fields upon pushing the Commit button would be far easier to code for supporting that scenario rather than coding validation on the AfterUpdate events of each control.