There a 3 type of alternative dol.
Note : usbloaderGX currently accept only the method 1.
Attention : it's not the real wdm format, it's only an example for understanding the chapter naming.
1. "Alt dol"
On games like metroid, you have 4 different dols (main.dol with menu, MP1.dol, MP2.dol and MP3.dol)
GX can select 1 dol at a time, in game preferences.
2. "Alt dol +"
With WDM, it's a text file with a list of dol, and a user friendly name
exemple :
mp1.dol -> Metroid Prime 1
mp2.dol -> Metroid prime 2 : Echoes
mp3.dol -> Metroid prime 3 : Corruption
Then, when booting Metroid prime trilogy, the loader show you a menu to let you select the chapter to play.
No need to go to the preference to select the dol.
3. "Alt dol+" too, but with parameter
Then, for Sam & Max 1 & 2, there is a possibility to specify which part of the same dol it must boot.
For example, imagine the dol is like this :
main.dol content = boot menu, boot option, boot chapter1, boot chapter 2, boot etc.
As you see, it's always the same dol, so there's an additional parameter (which works only for sam & max)
main.dol,1 -> menu
main.dol,2 -> option
etc.
(If I said anything wrong, please Wiipower, correct me !)