Can Active Item Qualities be activated multiple times on a single combat check? From the descriptions it's clear that Auto-fire, Sunder, and Linked can be; but the wording on Sunder is implicit and the wording for Auto-fire is explicit. Linked is limited in number of activations. Since I haven't been able to find any other wording that clarifies the topic and I don't know how to extrapolate from Sunder or Auto-fire, I'm at a loss.
What about other qualities? For some multiple activations would be redundant (like Knockdown), but it would make sense to activate qualities such as Stun multiple times.