title: Angular CDK understanding the overlay position system
body: <p>I'm really trying to understand the overlay position parameter but without any luck. I also can't find any documentation about this topic.</p>
  
  <p>What does the following code mean?</p>
  
  <pre><code>const positions = [
    new ConnectionPositionPair({ originX: 'start', originY: 'bottom' }, { overlayX: 'start', overlayY: 'top' }),
    new ConnectionPositionPair({ originX: 'start', originY: 'top' }, { overlayX: 'start', overlayY: 'bottom' })
  ];
  this.positionStrategy = this._overlay.position()
  .flexibleConnectedTo(this.getConnectedElement())
  .withPositions(positions)
  .withFlexibleDimensions(false)
  .withPush(false);
  </code></pre>