I've just been looking at using the Logging/Targets and (to me) it seems rather odd to have a drop-down box on the page that has "Nothing selected", to me that seems to imply that no 'Applications/log levels/facilities have been selected.
If you look at the Full Help and see that it says this:
QuoteChoose which levels to include, omit to select all
I would guess that the definition of 'omit' in this usage wouldn't be that clear to most people and perhaps it would be better to have "All Selected" (and have them ticked in the drop-down) as the initial 'selection' to make it clear that all of the items in the drop down list have been selected?