<Tr> <Th> 15 </Th> <Td> HSOn (0) </Td> <Td> Ground </Td> <Th> 65 </Th> <Td> Ground </Td> <Td> HSIn (11) </Td> </Tr> <Tr> <Th> 16 </Th> <Td> Ground </Td> <Td> HSIp (0) </Td> <Td> Lane 0 receive data, + and − </Td> <Th> 66 </Th> <Td> HSOp (12) </Td> <Td> Ground </Td> <Td> Lane 12 transmit data, + and − </Td> </Tr> <Tr> <Th> 17 </Th> <Td> PRSNT2 #</Td> <Td> HSIn (0) </Td> <Th> 67 </Th> <Td> HSOn (12) </Td> <Td> Ground </Td> </Tr> <Tr> <Th> 18 </Th> <Td> Ground </Td> <Td> Ground </Td> <Td> </Td> <Th> 68 </Th> <Td> Ground </Td> <Td> HSIp (12) </Td> <Td> Lane 12 receive data, + and − </Td> </Tr>

How many types of pci express slots are there