From what I've seen, the way you can use the linearts is like this;
If you have a design already in the lineart? You're good.
If your making a design in the lineart? You're good.
If your using the lineart to sell as 'Comissions' (As in using the lineart to create art of a pre-existing design for another player), You are breaking a rule.
Which doesn't really make sense but that's what I've seen. Which is completly twisted. The mods defiently need to contact Eve and discuss what the restrictions of the lineart is because it's rediculous that some poeple (like Sweetfire) have had their shops closed while other people are making profit while not having a single issue!