R1 is home reserve. You are at your home and have either five hours or ten hours depending on time of day to depart from your gateway airport. By the new contract it appears the company is responsible to get you from your home to your gateway but I'm not sure. I live out in the sticks and it's better for me to get myself there.

R2 is hotel reserve. It can be in your base or at another location. The company provides the hotel in either case but you do pay tax on the imputed income if you are in your base.

R3 is hot reserve at the airport. You have to be able to block out 1+30 from being called. I've not yet run into anyone who has ever been assigned R3.