This is the IEC 61970 CIM version number assigned to this UML model.
No Additional PropertiesForm is YYYY-MM-DD for example for January 5, 2009 it is 2009-01-05.
Form is IEC61970CIMXXvYY where XX is the major CIM package version and the YY is the minor version. For example IEC61970CIM13v18.
Used in RAVENS Schema to identify the corresponding CIM Object Type of the JSON object.