Hi
Since PAPs is primarily an image handling enhancement for product attributes, it doesn't actually define the relationships between attributes, only associates images with them.
What you could do with PAPs 'out-of-the-box' is use composite images to link Size and Color attributes.
You would use Linked Attribute Pictures (LAPs) by uploading a separate image for each possible combination of Size and Color, so for example you'd upload separate images for 'XL' and 'Pink', 'XL' and 'Blue', 'L' and 'Pink' etc.
If there was a particular combination which you didn't supply, you could upload an image for combination with just plain text saying something like 'Combination Not Available' to inform the customer that you don't supply it.
However, in this situation the customer could still go ahead and add the unavailable combination to the cart despite the message appearing, because there would be no native logic in Zen Cart code to prevent that from happening.
Alternatively, you could use PAPs in conjunction with another mod called 'Stock By Attributes', available here:
www.zen-cart.com/index.php?main_page=pro...&products_id=310 , which shows the remaining stock level of each attribute in the native attribute selection dropdowns. With this mod, you could just use PAPs as more of a gallery to view the combinations, with the selections actually being made via the dropdowns.
This to, though, wouldn't quite fit your requirement exactly. If you look on the support forum site for that Stock By Attributes mod, you may find other people who have had your requirements in the past and there may be more information there to suit your needs. On the other hand Stock By Attributes doesn't handle images at all, so maybe a combination of that and PAPs would be the best way to go.
Kind regards
PAPs Team