> For the complete documentation index, see [llms.txt](https://docs.opencutlist.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.opencutlist.org/features/parts/formulas.md).
# Formulas
Formulas allow you to greatly customize output data.
## The power of Ruby
When a formula field is available, OpenCutList gives you access to a list of variables where you can play with their data by writing [Ruby](https://www.ruby-lang.org/fr/documentation/) code.
Each variable as a [Data Type](/features/parts/formulas/data-types.md) that allows you to access some properties and functions.
## Formula field
The formula field is a text form field where you can write Ruby code. To display the list of available first level variables, type the **@** character. The list of variables may differ from form to form.
With formulas you can perform various things, from concatenate or decorate texts (string) ...
... to more complex operations with conditional structures.
