[BetterRed]

@deddajay

The ability to 'mark books' has been in calibre since version 0.7.49, but its only with introduction of the Mark Books feature in version 1.6.0, that they've been visible in the GUI.

To get round the 'problem' with Find Duplicates (FD), I (re)install the PI as and when required (I don't use it often) and remove it when I'm done. The duplicate exclusion marks are retained internally between (re)installs.

In the interest of performance the FD PI does the re-marking of exclusions when Calibre starts. IMO it would now be better to do it at the start of each Find Duplicates execution and suffer the performance penalty. But I suspect that under the new database backend that penalty may not be as much as it was previously.

Depending on your usage, you could clear the FD exclusion marks when calibre starts - and when you want to run Find Duplicates you could just do a restart. I should try it myself.

I think there's at least one other PI that marks books; might be Import List or Reading List or maybe both, but the marks don't 'stick' so they're not such a problem. And the Temp Mark PI marks books as does Add Books if you tick the box .

I think I suggested somewhere that when mouse pointer is hovered on the pin it could show the reason for the mark... 'user', 'add books', duplicate exclusion'... but it didn't get taken up. In the case of kiwidude's PI's, I'm pretty sure the 'mark-data' contains a string indicating reason for the mark.

BR