Definol information?

Does anyone have any info on this old developer? Barry Thornton refers to it in his books and in looking just now, I didn't find anything on the net.

Wasn't it a Johnson's proprietary liquid developer. Somewhere I have an advert which lists it. From memory it was an compesating high acutance developer introduced in the 1960's and was still in production until the late 1970's

Not sure what the developing agents werebut Johnsons had some of their own unique agents like Meritol.