On 21 Aug 2018, at 17:46, Phake Nick <c933103@gmail.com> wrote:
>
> Wikipedia Pinyin Chinese (coded for now as cmn, Mandarin Chinese): Here's a proposal that I think needs some serious discussion. Please read the discussion on the linked Meta page.
>
> Arguments against:
>       • No separate ISO 639-3 language code

Not necessary as the IANA script code extensions can be used, so zh-Latn-pinyin

>       • It is proposed that this can be handled with a script converter, per (for example) T193366.

This will never add in capital letters correctly.