The first tier, usually known as Tier 0 and sometimes known as "Basic", consists of the basic units that can be constructed from production structures without the need of any other structures.
Some examples of these units are basic infantry (assault and anti-tank/anti-air), basic vehicles (anti-infantry, anti-air, and possibly MBTs), and basic aircraft (fighters, light helicopters).
The second tier, usually known as Tier 1 and sometimes known as "Standard", is unlocked by the following structure:
- Detention Camp (USA)
- Propaganda Center (China)
- Black Market (GLA)
- Weapon Bunker (Russia)
- Solar Reactor (ECA)
Tier 1 unlocks heavier vehicles, mid-level aircraft, and specialized infantry, as well as the next tier of structures.
The third tier, usually known as Tier 2 and sometimes known as "Advanced", is unlocked by the following structure:
- Strategy Center (USA)
- Breeder Reactor (China)
- Chemical Lab (GLA)
- Industrial Plant (Russia)
- Research Facility (ECA)
Tier 2 consists of heavy artillery, heavy anti-air, hero units, secondary economy structures, super-weapons, and all other locked units.
Only available for the ECA, the fourth tier, usually known as Tier 3 and sometimes known as "Prototype", is unlocked through the Battlefield Prototypes Generals Promotion unlock, which allows the player to select one of the following research protocols at the Research Facility:
Each of these research protocols allows the use of unique units, abilities, upgrades and add-ons.