Questions regarding Exact Mirror Mode Settings

[Ivangelion]

In the Exact Mirror Mode Settings, there is an area called "Removal of Deselected Items from Destination", and it has 3 options:

Remove Deselected Subfolders And Files From Destination
Remove Files That Do Not Match The File Masks From Destination
Remove Files That Do Not Match The Filters From Destination

I've googled and searched the forum and didn't find anything related to this. What do all these mean?
Thank you.

[superflexible]

These should be used rarely. It sounds like you do not need them. These options can cause files to be deleted from the destination even though they are still on the source side. For example, if you have deselected some subfolders, the first option causes the deselected subfolders to be deleted from the destination.