Are there different types of total-etch bonding agents?

Multiple bottle systems that use phosphoric acid are called 4th-generation bonding agents, whereas single-bottle systems are called 5^th-generation bonding agents. The 4^th-generation systems provide the etchant, primer and resin adhesive in three separate containers. Examples of 4^th-generation bonding agents are 3M ESPE Adper Scotchbond Multpurpose Plus (3M ESPE) and Optibond FL (Kerr Corporation). The 5th-generations systems provide the conditioner and a primer-adhesive in two separate containers. Examples of 5th-generation bonding agents are 3M ESPE Adper Single Bond Plus (3M ESPE) and ONE-STEP (Bisco Dental Products).