Define or disambiguate "nonphysics"

In standard names, such as `tendency_of_water_vapor_mixing_ratio_wrt_moist_air_due_to_nonphysics`, the term, `nonphysics` has no definition. I feel like we should either have a definition (e.g., `nonphysics` == `dycore`) or break up the term into a set that _does_ have specific definitions.