From what I have read and game design books, apparently today, developpers have to possibility to change game variables and other in game information while the game is running instead of stopping the game, recompiling and starting the game again.

For modding purpose, it would be interesting to be able to change xml variables while the game is running. I am not quite sure how the changes could be applied afterward. Maybe the changes are done the variables in memory and it keep tracks of a list of the changed. Then when you exit the game, you can select which variables you want to save in the xml file.