Filtering using Themes, Categories and Signatures

This article is for IT Support.

School Manager uses Themes, Categories and Signatures to identify and filter the internet. You can use a combination of these to create Content Filtering policies that meet your school’s specific needs.


Themes are collections of similar websites and can include content Categories and Signatures.

Themes can have one or more Categories. 

When you use School Manager to apply a content filtering policy to a Theme, the policy is applied to all the Categories and Signatures.


Categories break the main Theme into more specific topics. Categories give you finer control over the content you’re blocking or allowing. If you apply a policy to a Category, it will only apply to content matching the Category.


A Signature is a pattern used to identify a specific website, group, or application. Not all sites and applications have a Signature. Signatures are usually only created for very popular sites and applications, or ones that need special treatment. However, every Signature belongs to a Category, and policies that affect this Category may also apply to the Signature.

Types of Signatures

While all Signatures are treated by the filter in the same way, there are three primary types:

Signature Type Description
Website A website Signature is the most common type is a website, web domain or subdomain. It affects all URLs in the domain and subdomains.
Group A collection of all the components required to identify a service, app or website. Group Signatures are used to identify online content dependent on one or more commonly blocked sites and services, such as Facebook.
Application A collection of the websites, connections, and ports an application or service uses to connect to internet services on different types of devices. This is most commonly used for streaming services and multi-platform games like Fortnite and Among Us or streaming entertainment like Netflix and Amazon Prime.


Filtering using Themes, Categories and Signatures

You can create policies using different combinations of Themes, Categories and Signatures. The policies are applied in the order, as listed in the Content Filtering page. This means that if you want to create an exception to a broader policy, the exception must be placed before the broader policy.

The following examples will use the main Business and Government Theme and its Categories of Business, Financial Services, Home and Real Estate, and Law and Government. The Financial Services Category also contains a Signature for the PayPal application.

Use Case Description Example Policy/Policies
Blocking only a Signature

To block just the PayPal Signature, you would create one policy.


if you already have another policy that allows either the Financial Services and the Business and Government Categories, you will need to place the Block PayPal policy above the main Category in the content filtering list.

  • Block PayPal
Allowing a Category while blocking the main Theme

To allow the Financial Services Category while blocking all other Business and Government content, you need to create two policies.


The Allow Financial Services policy must be listed before the Block Business and Government policy.

  • Allow Financial Services 
  • Block Business and Government 
Allowing a Signature but blocking its Category

To allow the PayPal Signature while blocking the Financial Services Category, you would create two policies.


The Allow PayPal policy must be listed before the Block Financial Services policy.

  • Allow PayPal
  • Block Financial Services
Allowing a Category while blocking a Signature If you want to allow the Financial Services Category while blocking the PayPal Signature and blocking all other Business and Government content, you would create three policies in this order.
  • Block PayPal
  • Allow Financial Services
  • Block Business and Government
Allowing a Theme

You shouldn’t need to create any policies to allow a Theme like Business and Government, because School Manager allows it unless you block it. If you have created a policy that blocks a Theme, deleting the policy will unblock it. However, if you want to allow a specific Theme, you would create one allow policy.


Locking an Allow Category policy stops any content in that Category from being blocked by any block policy that isn't also locked.

  • Allow Business and Government
Block a Theme To block everything in the Business and Government Theme, you would create one policy. This would block everything in the Business and Government Theme and everything in its Categories (Business, Financial Services, Home and Real Estate, Law and Government).
  • Block Business and Government
Blocking only a Category

To block just the Financial Services Category, you would create one block policy.


If you already have another policy allowing the Business and Government Theme, you must place the Block Financial Services policy above it in the content filter.

  • Block Financial Services


Frequently Asked Questions

How do I find out what Category a site is in?

You can use the Category Search to find out what Category a site or Signature is in.

Can a site or signature be in multiple categories at a time?

No. Sites, applications, and Signatures can only be assigned to one Category at a time. However, if the site is assigned to a subcategory, policies that affect the main Category may also affect the site.

How are sites and applications added to Themes, Categories, and Signatures?

Linewize adds sites to Themes and Categories and creates new Signatures in a few different ways.

  • Linewize Cyber Safety Team
    Our cyber safety experts regularly investigate and classify websites and groups of related content.
  • Requests for Review
    Linewize accepts requests for Signature review and recategorization from our users.
  • Partner Companies
    Linewize works with companies that are categorizing sites on the internet.

How do I change or add a Theme Category or Signature?

Contact Linewize Support with the details of the site or Signature and request a review. Our Cyber Safety team evaluates the request and makes updates to fit all of our users.


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