Confirmation on draining my water heater with this unusual (to me) drain valve

[Ed in Virginia]

Woke up to a leaking water heater. I've shut off the power and the cold water valve. The next step is to drain it, but I've not seen a water valve like this before. Is the cylindrical piece with the screwdriver slot used to relieve air pressure when draining? If so, do I just loosen it a bit and then open the valve to get her draining? I don't want to assume anything and have 80 gallons of water flooding our downstairs. Thank you in advance for any tips or advice.

 

[Breplum]

it is a normal drain valve. they don't put a handle on them to prevent dummies or children from tampering.
Multi-turn valve it is.

 

[Sponsor]

 

[Slomoola]

You need a full bore 3/4" ball valve. Those factory ones are too small inside and don't allow proper/thorough draining.