days do not have an upper bound; therefore you see 8bits on the most left position. Hours can be at most 24, so 7th bit is not present, minutes&seconds can be a

days do not have an upper bound; therefore you see 8bits on the most left position. Hours can be at most 24, so 7th bit is not present, minutes&seconds can be at most 60 so 8th bit is not present etc...