Ah i never realised it could be used as an ACTUAL developing agent, I might give that a try, I don't reckon it would last long once mixed? like rodinal as Vitamin C is unstable Also, what about using a salt of ascorbic acid, such as sodium ascorbate? does it require the molecule ascorbic acid on its own or can it still do its action, bound to the sodium? Also what about ascorbic acid esters? I always knew sodium ascorbate to be more stable, at least I think it is...
In XTOL it is sodium isoascorbate. Not sure if that helps answer your question (I'm not a chemist).
Isoascorbic acid is slightly more active as a developing agent. This isomer is more commonly called erythorbic acid. The sodium salt of either agent can be used in developers and do not require added alkali as the acid does. Erythorbic acid also tends to be a bit cheaper. What does the developing is the ascorbate ion which is produced by either ascorbic acid (think hydrogen ascorbate) or sodium ascorbate when dissolved in water.