Edition 1.0 of the spec allows implementations to support a normalization property or "kk" key to turn off normalization and then not meet the requirement that canonically equivalent strings must compare as 0. At the September 2012 TC 39 meeting, Erik Arvidsson criticized this as a pure optimization feature, and pointed out other ways to optimize within an implementation, e.g., by tagging normalized strings. Other ways to support optimization in applications that are sensitive to Collator performance would be API-level support for normalization or for collation keys.
We should consider removing support for this property from the API.
After discussion at the meeting of the Internationalization ad-hoc group 2012-10-05 and a subsequent proposal on es-discuss, the normalization options property and support for the kk Unicode locale extension key were removed from the Final Draft of Edition 1.0, 2012-10-12.