Not the same as replenishing. It means to restrain or hold back an active or over active developer. (Replenishing means to add new developing agent to exhausted developer as an economical alternative to making fresh developer.) I think restraining is done with bromide sometimes added to the mix. I'm sure there are other restrainers too. I think it is for less acutance (edge sharpness due to Mackie lines) and finer grain, but I'd have to look it up. Bump for you because I'm interested to hear what others more knowledgeable have to say.