Often there are quests like
https://www.wowhead.com/quest=35350/queen-of-the-clefthoof (Alliance)
https://www.wowhead.com/quest=35375/queen-of-the-clefthoof (Horde)

Those are clearly just copies of each other with some small differences, in this case the most obvious one, the faction.

When you hand those kind of quests in, sometimes the came marks the opposing one as complete as well, sometimes they don't.

Sometimes the quest equivalent on the other side is obvious as it has almost the same description or the same name, sometimes the chain is quite similiar but one step is different.

I am usually in favour of marking all these versions as I: for the other.
But we cannot tell the difference from an I: Tag wether it is decided by the author of that line or by the game.

Therefore i suggest to split this into two tags, one "verified by IsQuestFlaggedCompleted" and one "a human deduced the connection between both". So we don't have to fight in commits and do not have to keep the I: in the comment which wholly can't display.

Having the correlation between quests in wholly , even though the game api doesn't mark them as completed together, helps a lot when comparing conditions for both factions and helps to find flaws in them.