Region subtags and orthographic variants (was: Re: registration requests re Portuguese)

[Yury]

(this came in just moments before my bowing out of the topic, so I just 
couldn't resist answering)

On 04/15/2015 02:41 PM, Doug Ewell wrote:
...
> My objections have been to the continued blanket assertions that a
> region subtag is *always* "unnecessary" or "extraneous" with a variant
> subtag for orthography. "pt-PT-ao1990" is the right tag if the
> dialectical conventions of Portugal are also part of the equation.

Any lingustic background for *this* assertion, then? The dialectical 
conventions of anything are (a) never confined to the borders of any ISO 
region sufficiently non-isolated (like, not a lonely island or 
mountain/river valley in Equat. Africa or New Guinea), (b) are typically 
occupying much smaller area than 'country-level' ISO regions -- like an 
area betwen several main watercourses.

So you would want something like '-adamscounty' or '-rivervalley' for 
situations like dialectal variation of standard orthography.

American usus of 'color vs. colour' kind does not comprise a dialect 
/per se/, that's why en_US is sufficient.

Oh, and by the way, what's the definition of 'dialect' which is actually 
referred to here and in rfc5646?

-Yury