[Michael R 1974]

The term microcontrast is used in discussing lens resolution and digital images. Can someone provide a link to a scienfific definition as to its use in analog film processing.

I remain sceptical as to what the OP wants consideriing the films he uses.

It's just local contrast on a small scale. Tonal boundaries. I doubt a rigourous definition exists, although it can be shown the density difference (contrast) between adjacent tones increases as scale (width, frequency or whatever else people call it) decreases, driven by edge effects.