# Troubleshooting template errors: blocks and lists

!!!info
When you create a new template, the lay out your template sections should match the shape of the data that you're displaying. Using the wrong layout can generate errors.
!!!

<div>
  <script async src="https://js.storylane.io/js/v2/storylane.js"></script>
  <div class="sl-embed" style="position:relative;padding-bottom:calc(45.78% + 25px);width:100%;height:0;transform:scale(1)">
    <iframe loading="lazy" class="sl-demo" src="https://app.storylane.io/demo/mvif1x2izcmj?embed=inline" name="sl-embed" allow="fullscreen" allowfullscreen style="position:absolute;top:0;left:0;width:100%!important;height:100%!important;border:1px solid rgba(63,95,172,0.35);box-shadow: 0px 0px 18px rgba(26, 19, 72, 0.15);border-radius:10px;box-sizing:border-box;"></iframe>
  </div>
</div>

---

**Sections** are the building blocks of templates. You can use them to contain headings and metadata, or nest other sections inside them.

When choosing a layout for your section:

- Use **lists**, **cards** or **tabs** when your data is in an **array**.
- Use **blocks** to contain simple data (eg a rights statement) or an individual item within an array.

## How can you tell if your data is an array?

Generally, your data will be an array if it can have **multiple values** of the same type, like identifiers, decriptions or materials.

You can also check the **indexed data** pane of the **other formats** tab to see the shape of your data.

Data shaped like this, with several numerical indices, **is an array**:

```
identifier:
    0:
        type: "object number"
        value: "L1340"
    1:
        type: "PID"
        value: "0O6V-000A-0000-0000"
    2:
        type: "display number"
        value: "L1340"
    3:
        type: "sort number"
        value: "l31340"
```

Data shaped like this, without indexed elements is **not an array**:

```
summary:
    title: "Portrait of Adeline Ravoux, the Innkeeper’s Daughter"
```

## Correcting templating errors

When you lay out a template, you may sometimes see an error like this:

!!!danger
The template definition for this section does not match the shape of data provided. Please review the configuration.
!!!

To fix this error, you may need to:

- Open the **template editor**
- Navigate to the **section** that's displaying the error
- Switch the **layout** to the correct layout for the shape of your data
    - A **block** for simple data (eg a title or a heading)
    - A **list**, **cards** or **tabs** for data in an array.