Leave this here, i am failed to google and i got from game files.
Xenonauts X-division Aliens Interrogation scheme, same for Ceasans and Sebillians, all higher techs dont ask previous but give it:
Leader class: Chieftain->Officer->Leader
Ship OPs: ScOp->CorvOp->LandingOp->CruiserOp->CarrierOp->BattleShipOp LScOp and DreadnoughtOp doesnt give previous techs.
Engi: Technician->Engi->Chief->HeadEngi
Medics: Medic->Physician->Doctor->Professor
WeaponSpecs: WS->WeaponOfficer->WeaponCommander->TacticalCommander
Navigators: Nav->Pilot->CruiserCom->FleetCom
Terror OPs, Base assaulters, Bomber operators: 4 numbered professions for each class.
Terror Warriors: TSoldier->TWarrior->TElite