Group tags may be nested to perform even more complex formatting.
+ +Be careful when nesting several group tags. The group tag works +very narrowly - it only looks at the column you provide it with and so +long as that column doesn't change, it keeps looping. E.g. if you have +3 levels and the value of the outermost column changes but the value +of the middle column doesn't, the inner group tag won't notice and +will continue to loop. A workaround would be to create a derived +column, which contains e.g. "$f1,$f2", and use that as the column for +the inner group tag. (See also this +bug).
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