ACE3/addons/attach/CfgMagazines.hpp

class CfgMagazines {
    class CA_Magazine;
    class B_IR_Grenade: CA_Magazine {
        ACE_Attachable = 1;
    };
    class SmokeShell;
    class Chemlight_green: SmokeShell {
        ACE_Attachable = 1;
    };
};