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
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