The question In Strongly connected tournament T.Is it NP-hard to find a minimum number of vertices(V1) which make T\V1 as non strongly connected tournament. was retagged twice, from the original "np" to add tags "graph-theory" (which makes sense) and "ds.data-structures" (which doesn't, at least to me). After checking the FAQ for MO about Community Wiki mode it seems retagging does not count to make a post into a community wiki, so I retagged it yet again.
My retag removes one of the tags that was added in a previous retag.
What should the etiquette be for retagging?
I would normally explain my decision to roll back or modify a previous edit. However, retagging doesn't request an edit comment, so even access to version control tools would not help much here. It would be nice not to have retag wars, but a meta question for every retag conflict seems too much overhead.
Moreover, if I remember correctly, some MO members were upset when Suresh retagged some old posts, causing them to be bumped onto the front page. Is this reasonable?