> For the complete documentation index, see [llms.txt](https://developer.abacum.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.abacum.ai/guides/import-api-guides/file-requirements.md).

# File requirements

The file types, CSV rules and column rules for each load.

Abacum can process a file only when it follows these rules.

## File type and size

* `.csv` or `.xlsx` only.
* Maximum 512 MB for each file.

## CSV files

* Wrap text values in double quotes (`"`). This is the text qualifier.
* Use a comma (`,`) as the column delimiter.

## Keep the columns the same

Abacum maps each file to the typing layer that you defined when you set up the dataset. Keep the same columns in every load, so that this mapping stays correct.

If the source structure must change, update the dataset setup in Abacum before you send the new file. See [Set up the Import API](/guides/import-api-guides/set-up-the-import-api.md).