what kind of Siege weapons can a Wyrm Sniper Archtype use?

[fader92805]

In Pathfinder Player Companion: Dragon-slayer's Handbook

it states under the Wyrm Sniper Archtype

"Artillery Proficiency: Wyrm snipers are proficient with light siege engines, in addition to the normal gunslinger weapon proficiencies."

I have looked all over and cannot find an example of a "light siege engine."