Devs are broken down into families; general purpose,
fine-grain, accutance, pushing, etc.
Species, genus, family, order, and on up towards
larger groupings. The specific placement of any one
developer will depend upon the criteria for placement.
Grouped within a family for example might be fine grain
one-shot concentrates. Long shelf life may be a genus
within that family of fine grain one-shot developer.
So a biological hierarchy of developers can be built
but the criteria must established. An example; my film
developer is species D-23, variety, very dilute one-shot.
The genus is two component, the family, metol only
developing agent. The order might be easy home
brew developers.
Other criteria might be considered, toxicity, odor, stain,
speed of development, etc. If interested in generating
a method for "selecting" a developer, first some
criteria must be chosen. Dan