====================================
2.0 Release Candidate 1 - April 2016
====================================
* Added Volcanic Ash Advisory, Tropical Cyclone Advisory, and AIRMET products
* SAF was replaced by AIXM 5.1 in IWXXM schemas.  SAF will no longer be released as part of the TT-AvXML schema package
* Rules added to restrict units of measure on individual fields (such as air temperature) to those allowed by 
    ICAO Annex 3 / WMO No. 49
* A GML 3.2.1 profile was created for use with IWXXM, this is distributed in the release package
* Examples updated to remove unnecessary AIM data portions which are unlikely to be of operational use
* UML model changes performed to support Enterprise Architect as the primary mechanism for generating XML schema
* METAR/SPECI depth of deposit is now nillable to allow for representation of both '//' and '99' from 
    ICAO Annex 3 / WMO No. 49
* Forecast position analysis is now only available on TC and VA SIGMETs
* METAR/SPECI autoHeightUnobservableByAutoSystem has been removed - this can be represented with a nilReason of 
    http://codes.wmo.int/common/nil/notDetectedByAutoSystem
* SIGMET speedOfMotion and intensityChange are now optional.  This matches what is specified in ICAO Annex 3 / WMO No. 49

====================================
1.1 - June 2015
====================================
* References to Common Code Table C-15 was changed to Common Code Table D-2
* Multiplicity of forecastPositionAnalysis in SIGMET was changed from [1..1] to [0..1]
* XMI of the package was imported into and aligned with the UML profile for GML in Enterprise Architect 12

====================================
1.0 - September 2013
====================================
* Cloud type (CB/TCU) was moved onto CloudLayer with cloud base and cloud amount
+ ABV/P and BLW/M (at least and at most) conditions are now reportable on prevailing visibility
    and mean RVR
* minimumVisibilityDirection quantity now has the appropriate registry entry and markup
* METAR/SPECI runway contamination is represented as a CodeList of fixed options in the registry 
    instead of as an unconstrained Measure type
* Updated documentation to be explanatory rather than regulatory.  "SHALL BE" and "WILL BE" 
    wording was replaced with alternative text
* Corrected informative notes on diagrams whose contents have changed in Amd 76
* Fixed incorrect link from MeteorologicalAerodromeReport to its trendForecast type to the 
    proper type (MeteorologicalAerodromeTrendForecast)
* MeteorologicalAerodromeTrendForecast may now (correctly) reference up to three weather conditions 
    instead of only one

====================================
1.0 Release Candidate 2 - May 2013
====================================
* Updated IWXXM to match anticipated changes in ICAO Annex 3 Amendment 76
    * Moved forecastPosition from VA/TC SIGMET onto SIGMET (all SIGMETs may have forecast positions)
    - removed braking action from METAR/SPECI
    * renamed frictionCoefficient to estimatedSurfaceFriction
    - removed 1-minute minimum/maximum for RVR
    + added significant wave height onto METAR/SPECI
* Package renamed from "ICAO Weather Information Exchange Model" to "ICAO Meteorological Exchange Model"
    to address translation issues.  The abbreviated model name "IWXXM" remains unchanged
* SIGMET amended to allow for cancellations, including supporting constraints
* TAF amended to properly allow for CORRECTED, AMENDED, and CANCELLED status with the appropriate rules
    on present and missing information
* Significant updates to documentation to improve correctness and clarity
* Added support for METAR/SPECI and TAF NIL reports
* CodeLists moved from MetBasic and METCE into IWXXM
* Measure types from MetBasic were changed into GML Measure types

* METAR, SPECI, TAF, and SIGMET now have the <<FeatureType>> stereotype
* Removed <<Type>> stereotype from a number of classes
* Corrected surface wind properties on TAF, including fixes to variable wind directions and averages
* AerodromeHorizontalVisibility fixed to no longer require a minimum visibility direction when
    minimumVisibility is reported
+ Added new constraint to MeteorologicalAerodromeObservationRecord to ensure that if prevailingVisibility
    is less than 1500m then rvr must be reported
+ Added constraint onto AerodromeObservedClouds to ensure that if amountAndHeightUnobservableByAutoSystem
    is true then no cloud layers are reported
- Removed constraint on reported surface winds on METAR, SPECI, and TAF when CAVOK is reported
+ Added constraint to ensure that reported clouds and weather are missing when CAVOK is true
* Renamed "Context Diagram: Present Weather" to "Context Diagram: Surface Wind"
* Fixed METAR/SPECI, TAF, and SIGMET to ensure that XML element order more closely matches that of the corresponding
    ICAO Annex 3 Templates
- Removed humanReadableText from all reports
* Clarified documentation on how "TX" and "TN" maps into IWXXM
* Corrected documentation and constraint to indicate that SIGMETs are reported on FIRs, UIRs, and CTAs rather
    than just FIRs
* MeteorologicalAerodromeForecastRecord amended to ensure the CAVOK constraint on horizontal visibility
    refers to the correct name ("prevailingHorizontalVisibility instead of horizontalVisibility)
* METAR/SPECI amended to allow any number of runway states
* MeteorologicalAerodromeObservationRecord.recentWeather now has cardinality 0..3
* AerodromeRunwayState.estimatedSurfaceFriction now has a constraint to restrict values between 0.0 and 0.9
* Renamed ceilingAndVisibilityOK to cloudAndVisibilityOK on all classes
* AerodromeObservedClouds stereotype changed so it is nillable
* "Terminal Aerodrome Forecast" changed to "Aerodrome Forecast" to match current ICAO definition
- Removed HTML-like styling from many parts of the documentation to ensure proper translation to XML
+ unreliableFrictionCoefficient boolean flag added to AerodromeRunwayState
* Added a boolean onto AerodromeRunwayState to support runway conditions being reported on all runways at once.
    Changed the names of similar constructs on AerodromeWindShear for consistency
* Removed nilReason URIs from the model.  All nil reason base URIs changed from ttp://data.wmo.int/def/nil-reason
    to http://codes.wmo.int/common/nil
* Changed SAF references to mirror changes to simplified AIXM representations
- cloudType removed from CloudLayer

=======================================
1.0 Release Candidate 1 - December 2012
=======================================
Initial model release including complete representations of METAR, SPECI, TAF and SIGMET
from ICAO Annex 3 Amendment 75.
