Having a low level discovery with many item prototypes:

• you want some items being excluded from creation
• you don't want to have a separate discovery rule for all meaningful combinations of needed/unneeded items

Currently this can already be achieved by using a macro function for history storage period. The function would evaluate to e.g. '90d' in case you need the item and to '' in any other case. Of course this is not the intended way of doing it and it also leaves you with many error messages for failed creation of items on the server.