From CAP413.
"When transmitting messages containing flight levels each digit shall be transmitted separately. However, in an endeavour to reduce ‘level busts’ caused by the confusion between some levels (100/110, 200/220 etc.), levels which are whole hundreds e.g. FL 100, 200, 300 shall be spoken as “Flight level (number) HUN DRED”. The word hundred must not be used for headings."
So in Australia it's Two zero zero, in 'CAA-Land' its Two Hundred
