Level of command
If we consider the actions of a real commander, it is easy to see that he can give an order at any time, but he cannot give several orders simultaneously, and in most cases orders have to go through the chain of command. But this principle is not met in classic implementations of realtime wargames with pause feature - while on pause you can give any number of orders, bypassing the chain of command.
In order to make the order system more realistic, the game limits the number of orders that can be given at each moment of time - the so-called level of command. This level is indicated by the blue bar at the top of the screen (this feature is disabled on arcade settings).
The player spends the level of command by giving an order. The order "cost" does not depend on the number of units receiving the orders. But the threshold after which the unit will carry out the order is different for different units, and depends on the chain of command. Well managed (have a link to the commander) units carry out the orders at almost any level of command, but units separated from the chain of command or demoralized - only at high level. The command threshold for a group of units is indicated by marks (line segment) over the level of command indicator. If one of the marks is outside of the current command level, part of the units would not comply with the order. Units not currently able to comply with the order (and currently selected) are indicated by a black icon.
Also, different groups of orders have different "cost". For example, micromanagement commands such as reversing or turning, are more "expensive" than group commands. Relative "cost" is indicated by a blue dot on the order button.
Level of command regeneration rate and its initial value depend on the number of commanders and their level on the battlefield. Also, the regeneration rate can be configured in the options.
The player can issue and cancel any orders without restrictions on the initial orders phase, before the battle begins.