SetupAction()

override bool SetupAction	(	PlayerBase	player,
		ActionTarget	target,
		ItemBase	item,
		out ActionData	action_data,
		Param	extra_data = null )

См. определение в файле ActionAttach.c строка 28

    {
        InventoryLocation il = new InventoryLocation();
        if (!GetGame().IsDedicatedServer())
        {
            EntityAI targetEntity;
            if (target.IsProxy())
            {
                targetEntity = EntityAI.Cast(target.GetParent());
            }
            else
            {
                targetEntity = EntityAI.Cast(target.GetObject());
            }
            
            if (!targetEntity.GetInventory().FindFreeLocationFor(item, FindInventoryLocationType.ATTACHMENT, il))
                return false;
        }
            
        if (super.SetupAction(player, target, item, action_data, extra_data))
        {
            #ifndef SERVER
            AttachActionData action_data_a = AttachActionData.Cast(action_data);
            action_data_a.m_AttSlot = il.GetSlot();
            #endif
 
            return true;
        }
 
        return false;
    }

Перекрестные ссылки ActionData, ActionTarget, GetGame(), InventoryLocation::GetSlot() и AttachActionData::m_AttSlot.