# 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.

<figure><img src="/files/DUFw27RPEgTOGGoZdeps" alt=""><figcaption><p>Decomposition Tree: Warning when using aggregated measures</p></figcaption></figure>

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.**

<figure><img src="/files/KGK9u4KWnrKJitYqyiuq" alt=""><figcaption><p>Custom Calculations in Decomposition Tree</p></figcaption></figure>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.infotopics.com/powerkpis/configuration/custom-calculations-in-decomposition-tree.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.