> For the complete documentation index, see [llms.txt](https://doc.sysdevmobile.com/kalipso5/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.sysdevmobile.com/kalipso5/developing/form/expressions/functions/functions-descriptions/string-functions/middle.md).

# Middle

This Function returns a *\<string>*, which is a substring of the specified **Source string**, starting at the **Starting position**, with the specified Length.

### Parameters

* **Source string** *\<string> -* String from where to extract a substring.
* **Starting position** *\<string> -* Starting position in the **Source string** of the string to extract.
* **Length** *\<numeric> -* Length of the substring to extract.

### Examples

* *Example 1*

Mid("Enjoy Kalipso.", 7, 7)\
**Result** = Kalipso

* *Example 2*

Mid("Enjoy Kalipso.", 0, 5)\
**Result** = Enjoy

* *Example 3*

Mid("Enjoy Kalipso.", 15, 2)\
**Result** =

* *Example 4*

Mid("Enjoy Kalipso.", 7, 10)\
**Result** = Kalipso.

{% hint style="info" %}
If you specify a **Starting position** higher than the length of the specified **Source string**, and empty string will be returned.
{% endhint %}

{% hint style="info" %}
If you specify a Length higher than the difference between the length of the specified **Source string** and the specified **Starting position**, the returned string will be the left part of the **Source string**, starting at **Starting position**.
{% endhint %}


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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, and the optional `goal` query parameter:

```
GET https://doc.sysdevmobile.com/kalipso5/developing/form/expressions/functions/functions-descriptions/string-functions/middle.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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.