# Special functions examples

### In this section

* [Returning a loop index](https://help.qlik.com/talend/en-US/data-mapper-functions-reference-guide/8.0-R2025-10/returning-loop-index)
* [Setting a byte offset in a flat structure](https://help.qlik.com/talend/en-US/data-mapper-functions-reference-guide/8.0-R2025-10/setting-byte-offset-in-flat-structure)
* [Setting a dynamic element size in a flat structure](https://help.qlik.com/talend/en-US/data-mapper-functions-reference-guide/8.0-R2025-10/setting-dynamic-element-size-in-flat-structure)
* [Setting a number of loop iterations in a flat structure](https://help.qlik.com/talend/en-US/data-mapper-functions-reference-guide/8.0-R2025-10/setting-number-of-loop-iterations-in-flat-structure)
* [Implementing validation rules](https://help.qlik.com/talend/en-US/data-mapper-functions-reference-guide/8.0-R2025-10/implementing-validation-rules)
* [Working with globalMap variables in a Job](https://help.qlik.com/talend/en-US/data-mapper-functions-reference-guide/8.0-R2025-10/working-with-globalmap-variables)
* [Working with an external map in a Route](https://help.qlik.com/talend/en-US/data-mapper-functions-reference-guide/8.0-R2025-10/working-with-external-map-in-route)