iPhoto: want to delete text in Description field

I am unable to locate the property that allows me to edit or clear the description field for a photo in iphoto. I have several photos that have a description and I want the field to be blank. IThe description field is located in the information box at the lower left in the iphoto program. The info panel contains title, date, time, rating, keyword, kind, size and description. Help please.


easiest version. Select some photos and run the script

tell application "iPhoto"
	set sel to (get selection)
	repeat with onePhoto in sel
		set comment of contents of onePhoto to ""
	end repeat
end tell