Should include advice on specifying what a letter is.

[spemberton]

Several specifications define "names". As one example, XML says (https://www.w3.org/TR/REC-xml/#NT-Nmtoken)

NameStartChar ::= ":" | [A-Z] | "_" | [a-z] | [#xC0-#xD6] | [#xD8-#xF6] | [#xF8-#x2FF] | [#x370-#x37D] | [#x37F-#x1FFF] | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF] | [#x3001-#xD7FF] | [#xF900-#xFDCF] | [#xFDF0-#xFFFD] | [#x10000-#xEFFFF]

NameChar ::= NameStartChar | "-" | "." | [0-9] | #xB7 | [#x0300-#x036F] | [#x203F-#x2040]

It is really not clear where these list of characters come from, and why some of these are acceptable as name characters, and others not.

Unicode has the concept of 'category values', http://www.unicode.org/reports/tr44/#General_Category_Values that classify characters as, for instance "Uppercase_Letter", "Lowercase_Letter", etc.

It seems to me that it would be good advice for specification writers to use the Unicode Category Values as basis for defining (amongst other things) names, rather than apparently randomly chosen lists of character numbers.

[duerst]

Unicode® Standard Annex #31, Unicode Identifier and Pattern Syntax (http://www.unicode.org/reports/tr31/) may be relevant here, although last time I had a look at it, I didn't agree with all of it.

[aphillips]

Is this addressed by the recently-added section in specdev found here?

[aphillips]

No response on the last comment. We appear to have addressed it. Please reopen if needed.