Pluses and minuses

(from old email on the idna-update list, slightly updated)

Pluses for IDNA2008

+ Major improvement in updating to Unicode 5.2

+ Major improvement in making process of updating to future Unicode versions mostly-automatic

+ Significant improvement in allowing needed sequences (combining marks at end of bidi label).

+ Significant improvements to the BIDI rules

+ Improvements in user expectations for special cases: sigma, sharp s, joiners

+ Improvement in clarifying that what people register is the unmapped form.

Minuses for IDNA2008

- Major interoperability/security issue with special cases, URLs going to different places

- Major interoperability issue with local mappings

- Significant interoperability issue by not continuing 2003 mappings

- Significant increase in complexity, reducing the likelihood of correct implementation

- Misleading information in Rationale (if anyone reads it).

- Small interoperability issue by excluding symbols, punctuation

- More fragile in that future Unicode versions require a manual step to avoid instabilities

- No requirements for stability: that all labels valid under VX (>= 2008) must also be valid under all future versions

- No process for CONTEXTO that guarantees stability