I'm leery of a pull-down menu simply because much of the information entered will be inaccurate unless there are two pull-downs each for height and width. A conversion function, if possible, would be valuable. The American Iris Society lists heights of Iris in Imperial with metric in parenthesis and I've followed that example going forward. Perhaps we could discuss appropriate equivalents as I've noticed centimeters are usually rounded to the nearest multiple of 5. Is this correct?
