NOTAM contains information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential for personnel concerned with flight operations. The text of each NOTAM contains the information in the order shown in the ICAO NOTAM Format and is composed of the signification/uniform abbreviated phraseology assignned to the ICAO NOTAM Code complemented by ICAO abbreviations, indicators, identifiers, designators, call sign, freguencies, figures and plain language. NOTAM are originated and issued for Bangkok FIR and is distributed in five series identified by the letters A,C,J,H and G as follows;