Here are a few common anti-siphon valve models with the valve control features labeled. Most other solenoid valves are very similar in design and use similar controls. The Anti-Siphon Vent is a feature found only on anti-siphon valves.
Additional articles on this website related to anti-siphon valves:
How to Install a Anti-Siphon Valve gives a general overview of anti-siphon valves including situations where they won’t work or will leak, as well as step-by-step installation instructions and troubleshooting problems related to installation.
Backflow Preventers will guide you in deciding if an anti-siphon valve is the best choice for your irrigation system.