Thank you for finding that, IDP; I've looking sporadically all day for that without being able to remember the "parasitic fly" part. 'Splains why I couldn't find it.
When we at the nursery a couple of weeks ago, for the garden plants, we bought corn and radish seeds, too. Nothing on either package indicated hybrid or heirloom, so I asked. Apparently, this is a "difficult" thing to find out, as I was shifted from person to person to THE person who knew how to look it up on the computer. None of them seemed particularly interested in the information, as though it was irrelevant, which I thought out-of-place in a nursery that prides itself on its quality plantings.
I will have to remember to look on the seed packets for the "code" CO explained.