> ## Documentation Index
> Fetch the complete documentation index at: https://docs.abbyy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Configuring Rules for a Numeric Field Element

> Restrict values for a numeric field element in ABBYY FormDesigner with an Interval Rule: set value spans, rename rules, and customize error messages.

You can impose constraints on admissible values for a numeric field element by using rules.

To add a rule, click the **Add…** button on the Constraints tab of the [element properties](/flexi-capture/form-designer/element-number-field-edit). In the Validation Rule: Select Rule Definition window that will open, double-click the Create New Rule ... item in the Interval rule list to create a new rule. The Interval Rule dialog box will open.

<img src="https://mintcdn.com/abbyy/8aWHPAJyzWmTqglX/images/flexi-capture/form-designer/int_rule.gif?fit=max&auto=format&n=8aWHPAJyzWmTqglX&q=85&s=31c93f91cd393ef137c49f4e3bcaf5cf" alt="" width="303" height="343" data-path="images/flexi-capture/form-designer/int_rule.gif" />

**Rename...** — Click this button to rename the rule. In the dialog box that will open, enter a new name of the rule and click **OK**.

**Span: from … to**:

* **Add** — Adds the entered interval to the list.
* **Remove** — Removes the selected interval from the list.

**Error message** — **Generate automatically**: If this option is selected, the text of the error message will be generated automatically. Deselect the option, if you wish to enter a custom text.