# File format transformers

Transformers are processes that evolve files from one file format to another before preserving the objects.

{% hint style="info" %}
**Note**: to select transformers and relate them to the preservation plan, we must previously have associated some characterizer to the preservation plan.
{% endhint %}

Transformers are configured by file format. The files of which file format has been identified in the characterization and matched with those configured in the transformers will be evolved.

We have to configure the following parameters for every transformer:

* **Regular expression:** to facilitate file selection or to filter to apply only to one subgroup. If left by default, it will affect every file.
* **Priority:** it indicates the order of execution of the evolution process, should there be more than one evolver. Contingent upon the configuration of the evolver parameters, a different execution priority may produce different results in the ingestion job.
* **Keep the original:** by default, original files are deleted after the file transformation in order to keep the most updated one and save physical space. If we also want to keep the original files transformed by the evolver, we must mark this option.
* **Mandatory:** if we mark this option, an ingestion job will end with error if the transformer could not transform a file (the execution will end with error).

{% hint style="info" %}
**Note**: it is recommended that later on in the creation of the preservation plan, we mark the ‘repeal changes’ option if we configure any transformer.
{% endhint %}

![](/files/-MjyloIatFZuTPz0rCEz)


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