[precis] Applying the rules three times to get a stable output string?

Christian Schudt <christian.schudt@gmx.de> Sat, 09 December 2017 15:37 UTC

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Subject: [precis] Applying the rules three times to get a stable output string?
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Hi,

RFC 8264 introduced these new sentences:

   under certain circumstances, such as when Unicode
   Normalization Form KC is used, performing Unicode normalization after
   case mapping can still yield uppercase characters for certain code
   points

   Therefore, an implementation SHOULD apply the rules
   repeatedly until the output string is stable


I could imagine these sentences refer to code points of the „Unstable“ category, but this category is unused.

Are there any concrete code points or input strings which show this unstable behaviour?
I am asking for some test vectors, i.e. an input string, which doesn’t have the expected output string after the first rule application, but after the second one.

Thanks,
— Christian