Criteria for languages?

[CE Whitehead]

Hi.  This is a follow-up to my previous (Wednesday, Nov. 25) post (http://www.alvestrand.no/pipermail/ietf-languages/2009-November/009620.html). 
1.  Latgalian and Latvian
I went through the rest of the Latgalian language links.

The problem for the first newspaper linked to, based in the heart of Latgalia, is that neither the Latgalian language newspaper supplement--"Moras zeme"--nor the Latvian language newspaper "Rezeknes Vestis" makes use of anything but a character set declaration as far as I can determine.
However the newspaper "Latgales Laiks" (http://www.latgaleslaiks.lv/lv/) does use a Latvian language tag because its language is Latvian, while the cultural supplement in Latgalian to this newspaper, "Latgalisu Gazeta," does not use a language tag (this seems to verify that tags are being used for Latvian but not for Latgalian, but read on).
  
The publishing house does provide keywords in English, Russian, and Latvian, using appropriate language tags for this section but otherwise does not use a language tag.

Two of the music groups are linked to via http://www.borowa.lv/  whose content-language is identified as Latvian; I don't know either Latgalian or Latvian so cannot say but assume for now that the content is standard Latvian.  
(I could not link to the groups' sites themselves.)

Several of the literature sites do identify that the content is Latgalian in the keywords--I assume that this is done in lieu of tagging the language.

Latgalian has been developing separately from Latvian since 1621 according to Wikipedia and for a time Latgalia was under Russia until opting to join Latvia circa 1920:

"The language or dialect is called Latgalian.