What are Mercenary Ammo/Fragments Regarded as?

I'm getting into the weeds of building my Merc (new to POE) and I'm unsure of how the game considers ammo skills when it comes to support gems.

So, ammo skills replace your basic crossbow attack with that ammo skill. Some support gems give bonuses to attacks ("Attacks are skills that directly use your equipped weapon to damage enemies.")

Since the ammo skill is shot from my weapon.... does shooting an ammo skill count as an attack?