(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:


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


    • 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: 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.


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:



And change BIDI from:

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


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.


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.