Priority of traffic on unshaped interfaces

[fireball]

I have a WAN, LAN, DMZ, and WIFI interface on my pfsense box. As I understand it (from what I have read) I can only traffic shape between the WAN and a single interface (is this true)?

So if I do this on the DMZ, such that I can slow down certain servers, etc. what does this do to my LAN and WIFI (opt iface) traffic? Will it have a lower or higher priority than the DMZ traffic? Or will it be comparable to a normal setting on the shaped DMZ?

I am interested both in how this affect LAN<->WAN traffic, as well as LAN<->DMZ traffic. (and the same for the WIFI interface)

Thanks in advance.