> For the complete documentation index, see [llms.txt](https://support.vlex.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.vlex.com/document-types/key-number-topics.md).

# Key number topics

The Canadian legal system organises its case law using a number system for different areas of law. You can browse vLex content using the **Maritime Law Book (MLB) Key Number System**; there are over 100 topics and tens of thousands of sub-topics.

Go to **Browse** and set your jurisdiction to Canada. Among the other options, you will see the **Key number topics** menu. Select it to explore the complete catalogue.

![](/files/-MfDhMWiY9HoATklTwEc)

{% hint style="info" %}
Combine key number topics with alerts and get notified about new case law that falls into any category.
{% endhint %}

{% hint style="danger" %}
Key number topics are only available up to 2017.
{% endhint %}


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://support.vlex.com/document-types/key-number-topics.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.