1. The "EXRULE" property can no longer be specified in a component.
2. The "THISANDPRIOR" value can no longer be used with the "RANGE" parameter.
3. The "PROCEDURE" value can no longer be used with the "ACTION" property.
4. The value type RECUR no longer allows multiple values to be specified by a COMMA-separated list of values.
5. x-name rule parts can no longer be specified in properties of RECUR value type (e.g., "RRULE"). x-param can be used on RECUR value type properties instead.