Reference block

hi, i want to ask about , what is the use/purpose of reference block in modular-admin-html V1. is that necessary and required for something
```html
<div class="ref" id="ref">
    <div class="color-primary"></div>
    <div class="chart">
      <div class="color-primary"></div>
      <div class="color-secondary"></div>
    </div>
</div>
```
