I am reading Goldberg's 'Invariant transformations, Conservation laws and energy-momentum' from 1980. He frequently uses the notion of a function group.
For example: "For any field theory whose field equations are derivable from an action integral defined over spacetime, invariance of its action with respect to a Lie group leads to a differential conservation law for each parameter of the group whenever the resulting field equations are satisfied. Invariance of its action with respect to a function (?) group leads to a set of differential identities for the field equations themselves --- one for each independent transformation in the group. When the field equations are satisfied, these identities yield conservation laws.".
I am familiar with Lie groups (which he mentions), but when I google `function group' nothing pops up.