Yes, Dimezone S is a derivative of phenidone, and can be substituted for phenidone in all formulas that require it. Those will include PQ (phenidone / hydroquinone) and PC (phenidone / ascorbic acid) formulas. Dimezone S is more stable in solution and is slightly better for film development apparently.
Originally Posted by analoguey
You can look up Patrick Gainer's vitamin C formulas on unblinkingeye.com. I believe they have been extensively repeated here on APUG and elsewhere. They give results similar to Xtol, which is an excellent developer, perhaps the best generally speaking.
If you want to make parodinal, which is a really useful and versatile developer (and cheap!), you can use my calculator. If you use proper chemicals and follow the instructions, I guarantee that you will not be able to mess it up.
If you are looking for fun, then check this out:
The secret with ascorbic acid developers is that the cheap vitamin C does all the heavy lifting, while the co-developer is only required in tiny quantities. In Xtol, it is Dimezone S. In Caffenol, it is caffeic acid. In my Rosmarinol, it is rosmarinic acid. Typically, one needs 0.1 to 0.2 g per liter of stock, to get a fully active developer. The upshot is that the developer is more friendly to your health, and to the environment.
If you like coffee, then Caffenol sounds like something you should try. jnanian is the APUG user with most knowledge on that developer, AFAIK.
You still haven't told us what film you want to use, and what subject matter you are after. Those things are sort of important in selecting a developer.