# Validation rules - Optionline 1.x documentation

> Minimum and maximum length, number ranges and steps, the most checkboxes a customer may tick, and file types and sizes.

> [!NOTE]
> This is part of **Optionline Pro**.

Optionline Pro adds limits to fields. The store checks them on the server when the product is added to the cart, and refuses it with a clear message when a value doesn't fit.

| Setting | For | The customer sees |
|---|---|---|
| **Length** (min, max) | Text, text area | "Engraving needs at least 2 characters." / "Engraving can be at most 12 characters long." |
| **Range** (min, max, step) | Number, quantity | "Width must be at least 10." / "Width can be at most 200." The browser's number box also keeps to the range and step. |
| **Most choices** | Checkboxes | "Choose at most 2 options for Extras." |
| **File types**, **Largest file** | File upload | "The file for Photo must be one of these types: JPG, PNG." / "The file for Photo is too large. It can be up to 5 MB." |

Leave a setting empty for no limit. Lengths count characters (an accented letter is one character), including spaces.

## Checks that come with the types

Some checks need no setting:

- A **number** must be a number; a **quantity** a whole number, not negative.
- A **date** must be a real date.
- A **colour** must be a colour code such as #1e73be.
- A **file** must really be of an allowed type, whatever its name says.
- A **required** field must be filled in, as in Optionline. A conditional field is only required while it shows.

## Without Optionline Pro

If Optionline Pro is deactivated, a field with limits is kept but not shown in your shop, rather than accepted without its limits. It's back when Pro is active again.

Source: https://extendiment.com/plugins/optionline/docs/1.x/validation-rules