How is classification of beta blockers?

1st gen (nonselective for b1 and b2 [propranolol, nadolol, Pindolol, Sotalol, Timolol) 2nd gen (b1 selective or cardio selective [atenolol, acebutolol, bisoprolol, metoprolol, esmolol]) 3rd gen (block a receptors selective nebivolol and nonselective carveilil and labetalol