Ah Ha! The developer under study was a PQ-TEA solution to which I added either nothing, sodium sulfite or sodium ascorbate. The activity of PQ + TEA + water was very low, about what one might expect from the phenidone alone at 0.02 g/l. The activity took a leap when I added about 8 g/l of sodium sulfite.
Starting over with just the PQ-TEA in water, the activity took an even greater leap when I added 4 g/l of ascorbic acid as the ascorbate.
In other words, it seemed to me that ascorbate and sulfite were performing about the same task in a PQ type of developer.
This information is not world shaking, but would have consequences for those who are trying to get the most image stain possible out of catechol or who want to put a complete developer in a glycol or TEA solvent. We have seen it work in Pyrocat MC. Perhaps it has some bearing on the theory of synergism insofar as the replenishment of the "main" agent can be done by the sulfite or by ascorbate instead of the "secondary" developer. It is not possible, at least by me, to determine which is which. A clue is the variation of the activity of metol when either ascorbate or sulfite is added to the solution, where it appears that either one has the same effect as replenishing the metol.
Anyway, it gives an old codger something to keep his brain going.