Change the "any" of "Any script subtag" and "Any region subtag" of UTS35
Any script subtag is in title case (eg, Hant)
Any region subtag is in uppercase (eg, DE)
Example: the maxmal form of ja-Kana-t-it is ja-Kana-JP-t-it-Latn-IT
Put any script subtag into title case (eg, Hant)
Put any region subtag int uppercase (eg, DE)
"The t Extension.... These subtags are all in lowercase (that is the canonical casing for these subtags)"
also BCP47 said
"An implementation can reproduce this format without accessing the
registry as follows. All subtags, including extension and private
use subtags, use lowercase letters with two exceptions: two-letter
and four-letter subtags that neither appear at the start of the tag
nor occur after singletons."
the region and script subtag in the tlang of t is surely "occur after singletons"
Also, Script code may appear in type of co keyword or nu keyword of u extension. Therefore, we should make it clear in the UTS35 those are only limited to unicode_script_subtag inside unicode_language_id and unicode_region_subtag inside unicode_language_id but not ANY of them.
also need to change the example to
Example: the maximal form of ja-Kana-t-it is ja-Kana-JP-t-it-latn-it