ALTLVDS pin parametres in assignment editor

Hello, I am so sorry, I am just new in this forum, and my english is not so good that's why I was not so clear.

I am using quartus 10.1 and stratix iv GX

I am working on a project to realize a DVI interface using serdes. I did all my blocs using sopc builder and megawizard.

on my output I must have 8 chennels of outputs (chR+, chR-, chB+, chB-, chG+, chG-) of one bit each one.

I used the ALTLVDS for the serdes then i had 4 outputs, and to have the (-) and the (+) for each one I used ALTIOBUF.

When I assigned the pins name in the assignement editor I don't know which caracteristic I must have to this pins.

hope I was clear and thank you a lot for your replay.

:)