Hehe. Was it an assumption, or a well-established fact?
They can't be challenged because they are facts. It's like challenging the speed of light, or additive color... Of course this digression is not helping to provide an answer to the question so I will stop right there.
Well, as I am siting here, I am wondering a bit what "Open standard" even means. I have to say, I am an old man so, maybe it's just over my head. Perhaps some people can give examples of an "open standard" and then I will see.
Nevertheless, I don't think that ILDA is necessarily an "open standard". I mean, it's certainly not "open" for anyone to make changes, or for that matter, to publish the document. The changes must be made by the technical committee, and then the document must be published by ILDA. I can say the EXACT same thing about the DMX-512 standard and ESTA, and many of the same lessons (and very time consuming additions) are parallels here as well. Do we consider DMX-512 to be an "open standard"?
Like I say, it really depends on what the word "open" even means.
In the case of DMX-512, it could be that ESTA makes the standards document available to everyone, even non-members. If that's the case, then it could be said that DMX-512 is "open" to the public. But at least for now, if what Sergey says is true, the ILDA file format document itself is only available to members, so in that way the ILDA format isn't even "open" to the public.
Bill