Ihor Radchenko <yantar92@posteo.net> writes:

> Then, please mention this in the NEWS. Something like "we drop
> extension support as it never worked anyway".

Fixed.  I also reworded the surrounding text to match.

> You may even drop append and use ,@options inside `(...). Not a big
> deal though.

Fixed.

> If value is invalid string (not an actual number), `string-to-number'
> will return 0. This may cause very strange export output I think.

Fixed and added two new tests:

- ox-html/mathjax-legacy-scale-invalid
- ox-html/mathjax-legacy-scale-invalid-message

Below, I attach the 7th revision of the patch.

Rudy