Versioning of WIGOS Metadata Model - wmo-im/wmdr GitHub Wiki
Three levels are considered for versioning:
x.y.z, where
x (major) Breaking changes in comparison to previous version, such as introduction of new relationships or changes of cardinalities that are not backward compatible.
y (minor) Enhancements and extensions, such as addition of a new feature type, or extension of cardinalities that are backward compatible.
z (fix) Fixes of the model, such as erroneous modeling of the WMDS as described in the WMO technical documentation, typos in the UML diagram, etc.