Resolved: The tag has been removed from all questions.
The tag metric-topology has been created recently. Currently it contains only a few questions. Neither the tag-creator nor any other user created the tag-wikicreated the tag-wiki.
As far as I can say from the questions currently tagged with this tag, they are about the topology derived from a metric. In my opinion, the already existing tag metric-spaces can be used for such questions. Probably also general-topology could be added to most of them.
So my suggestion is to remove the metric-topology tag. (Or, if you think it is a better way, make it a synonym of metric-spaces.)
