Any rules against turning a wet bar into full kitchen in DC?

[Isaac Passmore]

So I'm seeing that a lot of SFHs in DC splitting the top and lower levels into two different spaces to rent out. Many of these basement units have what are called 'wet bars'. What do they mean when they say this? Is it simply just a sink and a mini-fridge? 

Do any of you know if there are any regulations or laws I should be aware of if I want to convert this 'wet bar' into a full kitchen which would include an oven and stove top?