> For the complete documentation index, see [llms.txt](https://chembl.gitbook.io/chembl-data-deposition-guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://chembl.gitbook.io/chembl-data-deposition-guide/~/revisions/t4ziM1Dk3kUY0U850C3g/file-structure/field-names-and-data-types-minimal-data-submission/controlled-vocabularies.md).

# Controlled vocabularies

Many of the fields in the data submission files are free text, i.e. the depositor can include any text in that field as long as it is suitable to describe the data they are depositing.

For a small number of fields this is not the case and a field requires a controlled vocabulary, a predetermined list of the entries that can be used in that field.  This helps users of ChEMBL to understand the data and to retrieve similar data more easily.

Controlled vocabularies are required for the TARGET\_TYPE field in the ASSAY file, and also for the ACTION\_TYPE field in the ACTIVITY file.