Many of our products are apparel based, and have both a size and color variant. Let’s say a shirt is available in red, white, and blue. Sizes are Small, Medium, and Large. Normally I would index this product with two different variants (size and color). However, for many of our products, certain size and color combos are not available. In this case, red/large doesn’t exist, and neither does blue/small. How do we exclude those variations from being indexed, and thus make them not show up in search results?