WUM is GNU/GPL software who can help you to :
- analyse a wii game iso file (or directly the DVD on linux) and tell you :

    * which is the region of the game (and other informations)
    * which is the region of the update
    * if there is a firmware update inside
    * if there is a risk to perform this update
    * if the update has already been modofied by WUM

- patch the update of this iso to :

    * put an inerte update inside : function Brick Block
    * replace by another update : can be use to make tests or unbrick semi-bricked wii

So using WUM will help you to understand better the iso file you want to play before insert it in your favorite console...

WUM is a GNU/GPL software, so you can check the source code to be more confident to use it.
But because WUM is a GNU/GPL software, be carefull from where did you downloaded it, prefer the official website : here;)