<Tr> <Th> FEV </Th> <Td> Forced expiratory volume (time): a generic term indicating the volume of air exhaled under forced conditions in the first t seconds </Td> </Tr> <Tr> <Th> FEV </Th> <Td> Volume that has been exhaled at the end of the first second of forced expiration </Td> </Tr> <Tr> <Th> FEF </Th> <Td> Forced expiratory flow related to some portion of the FVC curve; modifiers refer to amount of FVC already exhaled </Td> </Tr> <Tr> <Th> FEF </Th> <Td> The maximum instantaneous flow achieved during a FVC maneuver </Td> </Tr>

The percentage of the fvc expired in one second