There was an agreed standard API (ref AU No. 240, page 10).
There is some documentation of the facts in an old incomplete FAQ which I never released at [link]
The real problem was that ROL refused to take a stance when it was required.
Our policy is to promote products which we can offer support for - how can we point customers to the local PC-Globe store knowing the support they will be given? Development must be sustainable without the need to cross-subsidise from other products.
I believe only the Simtec solution allows for this, and the fact that other commercial developers have released code for this stack only reinforces this view.