> For the complete documentation index, see [llms.txt](https://docs.infotopics.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.infotopics.com/powerkpis/configuration/custom-calculations-in-decomposition-tree.md).
# Custom calculations in decomposition tree
For the decomposition tree, **data gets aggregated in the extension**. Thats why pre-aggregated fields like AGG(Profi Ratio) **are not allowed** to be used in the extension.
Decomposition Tree: Warning when using aggregated measures
To decompose calculations like a Profit Ratio, they **have to be calculated in the extension**. You can do this in the **Custom Calculations** section. All parts of the calculation have to be present in the **Measure Values shelf.**
Custom Calculations in Decomposition Tree
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