The problem was there was no _specification_. It was a 'how to use' summary, And each implementation could be (and was) different in subtle edge cases.
The point of CommonMark was to define the specification and stick to it.
I agree with GP, I thought it rather sucky that he objected to using the name.
Various markdowns have extension mechanisms, they always have. That's not what the GP was talking about.
The problem was there was no _specification_. It was a 'how to use' summary, And each implementation could be (and was) different in subtle edge cases.
The point of CommonMark was to define the specification and stick to it.
I agree with GP, I thought it rather sucky that he objected to using the name.
Various markdowns have extension mechanisms, they always have. That's not what the GP was talking about.