Hmm, I may not be understanding the type of data it is then. I'm not totally sure I understand what you mean by tabular data, is that the data in the drop-downs, such as in Model Age Disclosure? I can see how that would be something different to handle.
But how would the data in a field like "Additional Model Info" or "Model Release IDs" be any different from the data in, for instance, "Title/Object Name". Just something simple I enter like "MR1234" or "PR: Joe's House" or the like?
That's what I'm really asking, sorry if I wasn't very clear: why can't "Additional Model Info" or "Model Release IDs" be chosen as a field to be exported the way other IPTC, EXIF, etc. fields can?
Reading your response again, I'm thinking maybe you thought I meant I wanted to be able to add one variable to the export fields and get ALL the "Models, Properties, and Artwork" fields at once. No, I can see how that would not work. I'm just talking about separate variables for each of the individual fields, just like with the other sections.