>>Is this what most of the US carriers use??? or is their another version?
Well, in practice, most U.S. carriers will have more restrictive duty limitations in their union contracts. Sometimes contractual duty limits will vary with local report report time. Also, in case of weather and mechanical delays, most contracts allow an extension of duty within FAA limits. Several major accidents over the years, e.g. Pan Am and KLM at Tenerife and American at Little Rock, have raised issues concerning fatigue and extension of duty limits.