<Tr> <Th_colspan="9"> SR latch operation </Th> </Tr> <Tr> <Th_colspan="4"> Characteristic table </Th> <Th_colspan="4"> Excitation table </Th> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> Q </Td> <Td> Action </Td> <Td> Q </Td> <Td> Q </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> 0 </Td> <Td> 0 </Td> <Td> Q </Td> <Td> hold state </Td> <Td> 0 </Td> <Td> 0 </Td> <Td> 0 </Td> <Td> X </Td> </Tr>

What is the purpose of the clock input on the operation of the rs flip flop