How to make a buff permanent?

Hello everyone! I met a problem when I was making some custom skills via dbc yesterday, that I found out some skills(buffs) can be cancelled by clicking its icon on the right corner of the screen, but some could not, I am wondering how can someone make a skill which can not be cancelled by clicking its icon, like there is some buff , you can only get rid of it when you die, is there a column in the spell.dbc controls this? thank you in advance!

— Canned message start —

This thread is not related to the official Trinity codebase and was moved to the Custom Code section.

Please read the stickies next time.

— Canned message end —

http://emudevs.com/showthread.php/2814-Core-Edit-How-to-Add-Or-Change-Aura-Timer here.