[Ietf-languages] Braille and sign writing

[Hugh Paterson III <[e-mail]>]

Greetings,

I have a question which might show my naivety... How does BCP-47 and the
language tag database at IANA treat Braille and Sign Writing?

If I am reading ISO 15924 correctly Braille uses the code "Brai" so there
would be a valid code for English used in the USA encoded via
Braille: en-Brai-US.  Is this example correct?

If I had a service which transformed written text to Braille the input
might be en-US or en-Latn-US and the output presumably en-Brai-US.

With regards to sign languages, if I use the language code "ase" which
modality is assumed, visual, textual or neither? Sign language can be
written using a system called sign writing.  References [1], [2].

For example, if I wanted to encode that a service was a transcription
service from visual ASL "ase" to "ase" encoded in sign writing, how would
those two strings look using BCP-47?

The reason I am asking is that I am describing services which when given a
text translate or transform the text into another language or format.
For example, going from Roman Script English USA to Braille Script English
USA. I am also doing speech to text and text to speech and video to text
for sign and sign writing to video. So in my case I am crossing modalities
and scripts. I am looking to tag the language format in both the input and
the output. I am wondering to what extent BCP-47 can handle these cases.

thanks,
all the best,
Hugh Paterson III

references:
[1]: https://www.signwriting.org
[2]:
https://www.signwriting.org/archive/docs13/sw1283_A_GRAMMAR_OF_SIGNWRITING_by_Stuart_Thiessen.pdf