[rules-users] Planner with a list of planning variables

Hello all, can I use as planning variable a list of values? Here's a test use case: planning a food recipe, where the recipe can have say maximally 5 ingredients (taken from the solution property, I guess). So far I could find in the examples and documentation, it's all about ONE planning variable in the solution, but here I'd need a LIST of such... is it actually doable this way? I cannot do it the other way around, as an ingredient may be found in more recipes... Many thanks, JC