How to add an image to the tiles by editing the DITA map

To edit the metadata in the DITA map to set an image to be displayed in a tile, follow these steps:
Open the DITA map in the Text editing mode of oXygen.
Add the following metadata information in the topicref element (or any of its specializations) for each first-level topic that will have an image displayed in the corresponding tile:
```
<topicmeta>
  <data name="wh-tile">
    <data name="image" href="img/tile-image.png" format="png">
     <data name="attr-width" value="64"/>
     <data name="attr-height" value="64"/>
    </data>
  </data>  
</topicmeta>
```
Note: The attr-width and attr-height attributes can be used to control the size of the image, but they are optional.