Filtering Using Categories and Signatures

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This article is for IT Support and Filtering Administrators.

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

Categories and Subcategories

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

Categories can have one or more subcategories. Subcategories break the main Category into more specific topics. Subcategories give you finer control over the content you’re blocking or allowing. If you apply a rule to a subcategory, it will only apply to content matching the subcategory.

When you use School Manager to apply a content filtering rule to a Category, the rule is applied to all the websites, Signatures, and any subcategories in the Category.


A Signature is a pattern used to identify a specific website, service, 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 rules 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 Categories and Signatures

You can create rules using different combinations of main Categories, subcategories, and Signatures. The rules 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 rule, the exception must be placed before the broader rule.

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


Allowing a Category

You shouldn’t need to create any rules to allow a Category like Business and Government, because School Manager allows unless you choose to block it. If you have created a rule that blocks a Category, deleting the rule will unblock it. However, if you wanted to allow a specific Category, you can create an allow rule:

  • Allow Business and Government


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

Blocking a Category

To block everything in the Business and Government Category, you would create one rule: 

  • Block Business and Government

This would block everything in the Business and Government Category and everything in its subcategories (Business, Financial Services, Home and Real Estate, Law and Government).

Blocking only a Subcategory

To block just the Financial Services subcategory, you would create one block rule:

  • Block Financial Services

However, if you already have another rule which allows the Business and Government Category, you will need to place the Block Financial Services rule above it in the content filter.

Blocking only a Signature

To block just the PayPal Signature, you would create one rule:

  • Block PayPal

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

Allowing a subcategory while blocking the main Category

To allow the Financial Services subcategory while blocking all other Business and Government content, you need to create two rules: 

  • Allow Financial Services 
  • Block Business and Government 

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

Allowing a Signature but blocking its Category

To allow the PayPal Signature while blocking the Financial Services Category, you would create two rules: 

  • Allow PayPal
  • Block Financial Services

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

The same logic is true if you want to allow the PayPal Signature but block all other Business and Government content. You would create two rules:

  • Allow PayPal
  • Block Business and Government

The Allow PayPal rule must be listed before the Block Business and Government rule.

Allowing a subcategory while blocking a Signature

Finally, if you want to allow Financial Services while blocking PayPal and blocking all other Business and Government content, you would create three rules in this order:

  • Block PayPal
  • Allow Financial Services
  • Block Business and Government

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 more than one Category 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, rules that affect the main Category may affect the site as well.

How do sites and applications get added to Categories and Signatures?

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

  • Linewize Cyber Safety Team
    Our team of cyber safety experts are regularly investigating and classifying 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 Category, website 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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