field_select is the pros internally used by the
"field select"
call, but the problem with radio button is, that the program has to guess, what the name of each option is. With a select box it is clear, because it is included in the option-tag. If the radio buttons and their captions are located in separate table cells (as it is in the default standard.adp form template), the caption is empty, so there is no way of determining the right option to choose. As you can see, in that list of choices given above, the second element (the caption) is always { }.
Does anyone know if it possible to select a radio button by its id? Or maybe it would be a good idea to extend the search for the caption on the whole tr the radio button is in.