According to course material IRT310 page 73, "you can create a layout module variant to include certain articles in a layout module version or to remove certain articles from a layout module version".
Say, you have already article 3600800 in layout module D1001TEST1, version 0000, with a max quantity of 10 BOX. Now you want to change the max quantity to 25 BOX for store D002.
You attempt to create a variant by transaction WLWBN > click on the layout version 0000 > click on the button "Layout Module Variant Maintenance" > click on "Create and Assign Variant" and assign the relevant store(s) here. Next you select article 3600800 with a certain unit of measure.
At the top of the screen you have two buttons: "Assign" and "Assign Exclusively". "Assign Exclusively" is used to exclude articles from the standard layout module version. This works very well. But in my example we need to use the button "Assign" to increase the max stock. This doesn't work. When I try to save a positive difference on the max stock of 15 BOX, I get the error message:
"Article 3600800 UoM BOX is already assigned to module D1001TEST1 version 0000".
How can that be? Does the standard layout module version block for maintenance of variants?