ICAO Meteorological Information Exchange Model (IWXXM) is a standardized format for exchanging meteorological information used in aviation. It's an XML-based model designed to represent aviation weather information, including reports like METAR/SPECI, TAF, SIGMET, and features/objects like ash concentration forecasts in the forms of polygons. IWXXM is part of the broader SWIM (System Wide Information Management) initiative within ICAO, alongside FIXM and AIXM.