# Directory: data-source-post-processing

The **optional** directory `data-source-post-processing` contains custom XSLT files.

See: [Directory: data-source-post-processing](../data-source-transformation/data-source-post-processing).

## Transformation Input

The root tag of the input xml (which is automatically provided by the software) is `<data-source-post-processing-input>`. Within that root tag OpenEndpoints will insert the data converted from the data-source-definition or - if applicable - the output from a previous data-source-post-processing step.

![directory data sources post processing input](https://cdn.openendpoints.io/images/gitbook/directory-data-sources-post-processing-transformation-input.png)

## Transformation Output

The root tag of the output (=the file that is generated by your XSLT) must be `<data-source-post-processing-output>`.

![directory data sources post processing output](https://cdn.openendpoints.io/images/gitbook/directory-data-sources-post-processing-transformation-output.png)
