The Unicode Character Encoding Stability Policies ensure that developers know what they can depend on between successive releases of the Unicode Standard.

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.Additionally, the wording for two earlier guarantees about General_Category and Bidi_Class have been clarified:

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.For the exact wording of these new and updated guarantees, see Unicode Character Encoding Stability Policies.