# Linking resources

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**Added in** `eventcatalog@3.42.0`

Use `appliesTo` to connect an ADR to the catalog resources it affects. When resources are linked, the ADR appears in the **Decision Records** section of each resource's sidebar.

![Decision Records section on a resource sidebar listing linked ADRs](/assets/images/linked-adr-document-1f0fd3c94f476bbedc3d1e104bde617d.png)

## Use `appliesTo`[​](#use-appliesto "Direct link to use-appliesto")

Add an `appliesTo` array to the frontmatter, specifying the `type` and `id` of each affected resource.

adrs/choose-kafka/index.mdx

```
appliesTo:
  - type: domain
    id: Orders
  - type: service
    id: PaymentService
  - type: event
    id: PaymentAccepted
  - type: channel
    id: orders-domain-eventbus
```

## Supported resource types[​](#supported-resource-types "Direct link to Supported resource types")

The following resource types can be used in `appliesTo`.

```
agent
service
event
command
query
flow
channel
domain
user
team
container
entity
diagram
data-product
```

## Pin to a specific version[​](#pin-to-a-specific-version "Direct link to Pin to a specific version")

By default, EventCatalog resolves the link to the latest version of the resource. Add a `version` field to pin to a specific version.

```
appliesTo:
  - type: service
    id: PaymentService
    version: 1.0.0
  - type: event
    id: OrderConfirmed
    version: latest   # explicit, same as omitting version
```

## How it appears in the UI[​](#how-it-appears-in-the-ui "Direct link to How it appears in the UI")

When a resource has one or more ADRs linked via `appliesTo`, a **Decision Records** group appears in that resource's sidebar. Each linked ADR shows its name and links directly to the decision page.

This means engineers reading a service or event page can immediately see which architectural choices affect it, without leaving the page.