CONTEXTO Proposal

(This dates from July 20, 2009, when the CONTEXTO issue was still open. It is now moot.)

I believe that none of the current CONTEXTO characters are really required to be CONTEXTO, and all should be simply PVALID.

Here are my recommendations in detail:

A. HYPHEN

The rule on HYPHEN is unnecessary, since it is a requirement of the DNS system anyway; this is completely redundant. So remove from Tables:

• • http://tools.ietf.org/html/draft-ietf-idnabis-tables#appendix-A.1

  • Appendix A.1. HYPHEN-MINUS

  • Code point:

  • U+002D

  • Overview:

  • Must not appear at the beginning or end of a label.

  • Lookup:

  • False

  • Rule Set:

  • True;

  • If FirstChar .eq. cp Then False;

  • If LastChar .eq. cp Then False;

Note that in Protocol we have:

4.2.3.1. Consecutive Hyphens

The Unicode string MUST NOT contain "--" (two consecutive hyphens) in

the third and fourth character positions.

The corresponding Lookup restriction is missing from Protocol and should be added.

B. ARABIC-INDIC DIGITS

The rule on these overlaps with Bidi, and would be simpler and more appropriately moved there, since these are all only of concern with Bidi processing. So remove:

• • http://tools.ietf.org/html/draft-ietf-idnabis-tables#appendix-A.13

  • http://tools.ietf.org/html/draft-ietf-idnabis-tables#appendix-A.14

And change BIDI from:

5. If an EN is present, no AN may be present, and vice versa.

To:

5. If an EN is present, no AN or EXTENDED ARABIC-INDIC digit (U+0660..U+0669) may be present. If an AN is present, no EXTENDED ARABIC-INDIC digit (U+0660..U+0669) may be present.

C. Other CONTEXTO

Remove the other CONTEXTO cases. These consist of only the following 6 characters, and there is no particular problem with making them all simply PVALID in the Exceptions table.