DHCP Relay - which ports are forwarded

Hi,

I came from Cisco world. In Cisco when we enable dhcp relay/ip helper, it not only forward DHCP broadcast, also total 8 UDP services.

http://www.ciscopress.com/articles/article.asp?p=330807&seqNum=9

In my case I need to forward port 138 and 139 (netbios).

Does anybody know which ports are forwarded when we activate DHCP relay on an interface? Is it only DHCP ports? Can we add any other ports additional to the DHCP ports?