Hi Freddy
The annotation means that the content of e.g the annotated section (which is the list of presentations) is shared with another section in a different editor. This means that changes to the content of the section (and not e.g. to the title of the section) affect this section in other editors, too.
Imagine you have a section which is not shared, the you add a section from a different editor using the 'Reuse Existing Section' variant, you will get a section that is 'shared' between the two editors. If you want to make a change to a 'shared' section that should not affect the section in other editors, you first have to duplicate the section to get an unshared copy.

Regards

Marcel
Jazz Work Item team