Only active when the CFD Enable bit in the Module Configuration Register is set (0x8000 bit 17)
  When enabled additional information is included in the data format

000   Time Stamp is 47 bits  (units 2 ns)

010   Time Stamp is 47 bits  (units 2 ns) + 10 bits 

101   Time Stamp is 31 bits  (units 2 ns)