I listed some most common recipes in attachment (most taken from Anchell&Troop: The Developing Cookbook). Anchell&Troop writes common developing directions for all DD-23 variants, but as this http://unblinkingeye.com/Articles/DD-23/dd-23.html explains, it's far from truth. Thornton also writes in his book Edge Of Darkness that DD-23 variants are easy and re-usable 'almost forever'. That differs a lot from Lipka's writings in linked web page. I have used Thornton's variant. Just because it was first one I learned. As there's so many variants, I would like to know how do they differ from each other? My limited literature and lot of googling I did, gave no answers.