Only land units,orbital fighters (orbital fighter only kills other orbital units), jigs and orbital factories (orbital factories for advanced orbital scout units)
A unit restriction capability is currently in development by a community member. See the 'in development' chapter here: https://wiki.palobby.com/wiki/PTE_Testing However, since PA development has stalled (as far as we know), the only updates pushed to the game are community updates. Alias the updates are made in the spare time of ex-developers and huge fans of the game. So don't expect an update soon.
