Attack Order
public class AttackOrder : Order
This class is used for attack orders for unit. It contains AttackTarget field, which stores target for attack of unit.
Example
// this example code running from Unit.cs component
Unit unit = this; // getting unit component, from which we run this code.
Unit enemyUnit = FindObjectOfType<Unit>(); // suppose that there we setting up Unit component of other unit.
AttackOrder order = new AttackOrder(); // creating new AttackOrder here
order.AttackTarget = enemyUnit; // setting up enemy unit as attack target.
unit.AddOrder(order, false); // adding created order to unit orders list. Now unit will follow other unit.