You must understand these terms as in M & B you get direct questions on them, however you shall have your CAP69. in the exam with you.
In simple terms BEM is mass of aircraft on ground with no crew, fuel (except unuseable) or passengers (traffic load). Once you add the crew and flight catering/equipment you get the Dry Operating Mass (DOM).
Then you add the passengers (traffic load) which includes their baggage. The DOM + Traffic Load = ZFM which must not exceed MZFM. Finally add the fuel which will give you Actual Take Off Mass, which must not exceed MTOM. On a normal landing the trip fuel has gone and the aircraft must not exceed the MLM.
ZFM is the actual mass of aircraft without fuel. Do not confuse with MZFM a limit set by Mr Boeing/Airbus.
As said above this is a simple overview and there is a little more to it than this.
Last edited by RichardH; 12th Jan 2012 at 12:24.