title: Docker Compose Syntax
body: <p>so I have been using docker compose for a while, I have recently come across this <em>new</em> syntax and I have no idea what it means:</p>
  <p>For example - the compose file is located here</p>
  <p><em><a href="http://airflow.apache.org/docs/apache-airflow/stable/docker-compose.yaml" rel="nofollow noreferrer">http://airflow.apache.org/docs/apache-airflow/stable/docker-compose.yaml</a></em></p>
  <p>It has things such as</p>
  <ul>
  <li>&amp;airflow-common</li>
  <li>&lt;&lt;: *airflow-common</li>
  </ul>
  <p>Could somebody explain to me what that means ? It appears to be some defining config and referencing it.</p>