<P> Indian Railways offers various travel classes on their coaches . Depending upon their travel class, the passenger cars feature different seating arrangements or berths subject to availability . </P> <P> The following table lists combinations of class - accommodations in normal operation . </P> <Table> <Tr> <Th> Class </Th> <Th> Description </Th> </Tr> <Tr> <Td> 1A </Td> <Td> AC first class: The most expensive class, with fares almost on par with airfares . There are eight cabins (including two coupes) in full AC first class coach and three cabins (including one coupe) in half AC first class coach . The coach has an attendant, and bedding is included in the fare . This air - conditioned coach, present only on popular routes, can carry 28 passengers (full coach) or 10 passengers (half coach). </Td> </Tr> <Tr> <Td> 2A </Td> <Td> AC two tier: These air - conditioned coaches have sleeping berths across eight bays . Berths are usually arranged in two tiers in bays of six: four across the width of the coach and two lengthwise across the corridor, with curtains along the corridor . Bedding is included in the fare . A coach can carry 48 (full coach) or 20 passengers (half coach). </Td> </Tr> <Tr> <Td> FC </Td> <Td> First class: Similar to 1A, but without air - conditioning . No bedding is available in this class, and the berths are narrower than 1A . There is an attendant . Only heritage trains still have this class . </Td> </Tr> <Tr> <Td> 3A </Td> <Td> AC three tier: Air - conditioned coaches with 64 sleeping berths . Berths are similar to 2A, but with three tiers across the width and two lengthwise for eight bays of eight . They are slightly less well - appointed, usually with no reading lights or curtains . Bedding is included in the fare . </Td> </Tr> <Tr> <Td> 3E </Td> <Td> AC three tier (economy): Air - conditioned coaches with sleeping berths on the Garib Rath Express . Berths are usually arranged as in 3A, but with three tiers across the width and three lengthwise . Appointments are similar to 3A but bedding is not included . </Td> </Tr> <Tr> <Td> EC </Td> <Td> Executive chair car: An air - conditioned coach with spacious seats and legroom . With four seats in a row, it is used for intercity day travel and is available on the Tejas, Shatabdi Express and Gatimaan Express . </Td> </Tr> <Tr> <Td> CC </Td> <Td> AC chair car: An air - conditioned coach with five seats in a row, used for intercity day travel . Air - conditioned double - deck coaches used on the Double Decker Express have similar accommodation . </Td> </Tr> <Tr> <Td> SL </Td> <Td> Sleeper class: The sleeper class is the most common coach on IR, with ten or more SL coaches attached to a train rack . They are sleeping coaches with three berths across the width and two lengthwise, without air - conditioning . They carry 72 passengers per coach . </Td> </Tr> <Tr> <Td> 2S </Td> <Td> Second seater: similar to CC, without air - conditioning . Double - deck second seaters are used on the Flying Ranee . </Td> </Tr> <Tr> <Td> UR / GEN </Td> <Td> Unreserved / General: The least expensive accommodation . Seats are not guaranteed . Tickets are valid on any train on a route if used within 24 hours of purchase . </Td> </Tr> </Table> <Tr> <Th> Class </Th> <Th> Description </Th> </Tr>

What is the meaning of 3 tier ac
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