Which concept generally preceded the specific form factor of integrated brake/shifter levers?

Answer

The function of indexing

The text indicates that the functional principle of indexing—the defined cable stops—existed in separate shifters (like downtube or bar-mounted) before manufacturers packaged that indexing mechanism with the brake lever into integrated units like STI.

Which concept generally preceded the specific form factor of integrated brake/shifter levers?
inventiontechnologymechanismbicycleshifter