> For the complete documentation index, see [llms.txt](https://help.bioinsight.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.bioinsight.illumina.com/clarity-lims/api-and-database/api-docs/cookbook/working-with-user-defined-fields-custom-fields/about-udfs-custom-fields-and-udts.md).

# About UDFs/Custom Fields and UDTs

In the BaseSpace Clarity LIMS web interface, in the Custom Fields configuration screen, administrators can add user-defined information by adding custom fields (global fields or master step fields). At this time, user-defined types (UDTs) are only supported in the API.

Use these custom fields to configure storage locations for data that annotates project, submitted sample, step, derived sample, measurement, and file information recorded in a workflow.

All XML element attributes and values are text. Before using the value in a script, you may want to convert to a strongly-typed variable such as a number or date type.

For details on the formats used in XML, see [Working with User-Defined Fields (UDF) and Types (UDT)](/clarity-lims/api-and-database/api-docs/rest/working-with-user-defined-fields-udf-and-types-udt.md).

{% hint style="info" %}
When updating multiple process outputs or containers, you can increase the script execution speed by using batch operations.
{% endhint %}


---

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