Tag IDs: monitor.php?q=tagid — alphanumeric, hyphens, underscores. Two-level: a1, a2 group under a; bar uses first sub-tag (e.g. a1) for percentages.
monitor.php?q=tagid
a1
a2
a
IPs appearing in all tags of a group get highlighted in the IP list. Use + to combine tags, e.g. a+b. Groups are ordered left→right; rightmost matching group wins. Highlight colour = last tag's colour in the group string.
+
a+b