Recent changes to these policies include new guarantees:
- Property aliases will not be reused later for different properties.
- Property value aliases will not be reused later for different property values.
- Characters with the General_Category of Number are guaranteed to have a corresponding Numeric_Type value.
- No new General_Category property values will ever be added.
- New Bidi_Class property values can only be added for a tightly constrained class of new character additions.