– Create a text field, I will call mine Revision_c , on Opportunity Revenue Object.
While creating this field add as default fixed value : Update 0
Now create a trigger on Opportunity Revenue of the type Before Update with the following code:
Now each time a new revenue line is added the field Revision_c with have the value Update 0.
After you make some changes to the revenue line and click save the value of field Revision_c, should change to Update 1 and so one, after each change the number should increment.