Define a regular expression for a variable

task brazil Updated Sep 10, 2026 1 min read define-regex-vrble.md

Define a regular expression (regex) to validate a variable value.

Before you begin

Role required: catalog_admin or admin

Procedure

Navigate to All > Service Catalog > Catalog Variables > Variable Validation Regex.
Click New.
On the form, fill the fields.

Field	Description
Name	Name of the regular expression.
Validation message	Message that appears when the validation fails.
Active	Specifies if the regex is active.
Regular Expression	Sequence of characters that define the format of the variable value.For example: Invalid Regex: /(((ftp\|http\|https):\/\/)\|(www\.))([-\w\.\/#$\?=+@&%_:;]+)/i Valid Regex: (((ftp\|http\|https):\/\/)\|(www\.))([-\w\.\/#$\?=+@&%_:;]+) Note: Ensure that the regex does not cause catastrophic backtracking. You should not use embedded flag expressions. Use the Regex Flag list for the ignore case.
Regex Flag	Character set that is considered while validating the regular expression.- None: No regex flags are applied. Case Insensitive: Enables case insensitive matching. Case insensitive matching assumes that only characters in the US-ASCII charset are being matched. Unicode-aware case-insensitive matching can be enabled by selecting Both as the regex flag. Unicode Case: (Reserved for future use) Same behavior as None. Both: Case insensitive matching is done in a manner consistent with the Unicode Standard.

4. Click **Submit**.

Parent Topic:Types of catalog items

Related topics

Create a service catalog variable

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---
title: Define a regular expression for a variable
description: Define a regular expression \(regex\) to validate a variable value.
locale: en-US
canonical_url: https://www.servicenow.com/docs/r/servicenow-platform/service-catalog/define-regex-vrble.html
release: brazil
product: Service Catalog
classification: service-catalog
topic_type: task
last_updated: "2026-09-10"
reading_time_minutes: 1
breadcrumb: [Types of catalog items, Explore, Service Catalog, Manage service capabilities, Extend ServiceNow AI Platform capabilities]
---

# Define a regular expression for a variable

Define a regular expression \(regex\) to validate a variable value.

## Before you begin

Role required: catalog\_admin or admin

## Procedure

1.  Navigate to **All** &gt; **Service Catalog** &gt; **Catalog Variables** &gt; **Variable Validation Regex**.

2.  Click **New**.

3.  On the form, fill the fields.

<table id="table_b1s_q5g_xfb"><thead><tr><th>

Field

</th><th>

Description

</th></tr></thead><tbody><tr><td>

Name

</td><td>

Name of the regular expression.

</td></tr><tr><td>

Validation message

</td><td>

Message that appears when the validation fails.

</td></tr><tr><td>

Active

</td><td>

Specifies if the regex is active.

</td></tr><tr><td>

Regular Expression

</td><td>

Sequence of characters that define the format of the variable value.For example:

-   Invalid Regex: /\(\(\(ftp\|http\|https\):\\/\\/\)\|\(www\\.\)\)\(\[-\\w\\.\\/\#$\\?=+@&amp;%\_:;\]+\)/i
-   Valid Regex: \(\(\(ftp\|http\|https\):\\/\\/\)\|\(www\\.\)\)\(\[-\\w\\.\\/\#$\\?=+@&amp;%\_:;\]+\)
 **Note:**

-   Ensure that the regex does not cause catastrophic backtracking.
-   You should not use embedded flag expressions.
-   Use the **Regex Flag** list for the ignore case.


</td></tr><tr><td>

Regex Flag

</td><td>

Character set that is considered while validating the regular expression.-   None: No regex flags are applied.
-   Case Insensitive: Enables case insensitive matching. Case insensitive matching assumes that only characters in the US-ASCII charset are being matched. Unicode-aware case-insensitive matching can be enabled by selecting **Both** as the regex flag.
-   Unicode Case: \(Reserved for future use\) Same behavior as **None**.
-   Both: Case insensitive matching is done in a manner consistent with the Unicode Standard.


</td></tr></tbody>
</table>4.  Click **Submit**.


**Parent Topic:**[Types of catalog items](https://raw.githubusercontent.com/ServiceNow/ServiceNowDocs/brazil/markdown/servicenow-platform/service-catalog/r_ExtendedCatalogItemFunctions.md)

**Related topics**  


[Create a service catalog variable](https://raw.githubusercontent.com/ServiceNow/ServiceNowDocs/brazil/markdown/servicenow-platform/service-catalog/t_CreateAVariableForACatalogItem.md)