Just make it very simple....If i have a archiving object and i need to run for a period 01-2008 to 03-2008 then i never bother about open documents or closed documents, instead i would simply create create a variant and will run, now all the closed documents will get archived and open documents will be untouched. Now i will close all the open documents and will run the same variant again so that the remaining open documents which are already closed will get also get archived.
With regards,
Tony.