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.

How to Repair a Anti-Siphon Valve

Rainbird Anti-Siphon Valve Leaks, Won’t Fully Close

Installing Valves Downstream from Anti-siphon Valve

How to Fix a Automatic Irrigation Valve that Won’t Open

Backflow Preventers will guide you in deciding if an anti-siphon valve is the best choice for your irrigation system.