@walter.arrighetti, I believe this stemmed from a request made by you when this group was first forming. And I may have misunderstood your intent, so let’s discuss as a group in this thread.
The desire here seems to be to better describe the intended input and output of a LUT - i.e. color primaries, white point, transfer function, viewing environment, etc. However, for whom is the “colorspace” being described?
Is it for an application to be able to parse and somehow use it? If so, I think that’s a noble, but unattainable goal. As mentioned during the call, this has been attempted by many groups in many other instances (e.g. DPX) and it has always failed. Enumerated lists always end up underspecified and so in practice end up getting ignored because they are never set properly.
If this item is solely intended as an informative field for the user, then how does adding another element to
OutputDescriptor help? Isn’t that what those two arbitrary string elements are already intended for?
During the call it was suggested we could potentially add optional attributes to the InputDescriptor and OutputDescriptor elements: such as ‘colorSpace’, ‘transferFunction’, ‘whitePoint’, etc. This would avoid adding additional levels to the XML structure and allow for arbitrary order/presence of these labels.
If we insist on adding some additional structure to describe the intended input and output, my vote is for doing it via attributes.