If you add a version field, you can add this set field step after duplicating the invoice record:
Set FIeld [Project::Version ; Project::Version + 1]
Then you can use an auto-entered calculation on yet another new field to combine the job number and the version values into a single value if such is needed. (You can use layout text and merge fields to display this same result without any added field to combine the two.)
__kp_Job_Number & "." & Version
also, recently i saw that you posted a link to the explainations on kp and kf field designations, etc.
Could you repost that?
kp stands for "primary key"--the field that is defined to uniquely identify each record in the table where the field is defined. kf stands for "foreign key", this is the match field in a related table--often it matches to the primary key field of the table to which it is linked, but not always.
I think this is the link you wanted: Common Forum Relationship and Field Notations Explained
Please note that this is a link that was originally started as an easy way to help folks understand the notation I most often use when suggesting a particular set of relationships. I think the naming convention that I use in it is pretty decent, but it's far from the only set of such "conventions" you might use.