Hi, Anat;
Did you have a proposal for how you would represent the upper and lower limits, as well as the nominal base, for your Rx ranges, using a model similar to what Steve proposed? At first glance it appears that Steve's proposal could handle this by adding two additional columns for min and max base curve, using the existing column to represent "preferred" base curve, perhaps. The end result would be more complex and require additional boundary identifiers, but I think it could work. Is this along the lines of what you had in mind? (I do not want to presume to speak for you on this, but because this seems to be a Shamir-specific request you might be best able to suggest how this could be represented).
A design such as you give may not be supported today by all LMS systems; I know in our case we would use upper and lower limits when they are provided by the LDS in response to a BRS request, which is what we do today for Shamir integrations, but we don't have a means of indicating multiple valid ranges of base curves for an Rx when we use a base curve chart. We can handle a 3-dimensional model, using sphere, cylinder, and add, but only to specify a nominal base.
Of course, whether LMS systems today can support it does not impact how and whether we represent it in a new standard.
Tony