When a user realize an updating, creation, or run a complex tunneling process, if after that you need to refresh a screen area without reload all, the action form need to know what it want to update.
This create a dependency between the screen where is displaying information and the updating form. Instead create more complicate case to pilot the dynamic interaction between the displaying result and the updating action, we change the reasoning. A user want a good displaying after his operation is finished, so after he terminated his process.
We introduce a new element, callback on the link. A user start a process in general after follow a link, and when is done, we follow the callback to call the area to refreah.
With this the developer is concentrate on the start and the end of a process. The form or the tunneling process isn't linked to the final screen.