Please explain this line of js code.
<p>I have the following javascript code block, and is not very clear about it:</p>

<pre><code>var level = this.getLevelForResolution(this.map.getResolution());
var coef = 360 / Math.pow(2, level);

var x_num = this.topTileFromX &lt; this.topTileToX ? Math.round((bounds.left - this.topTileFromX) / coef) : Math.round((this.topTileFromX - bounds.right) / coef);
var y_num = this.topTileFromY &lt; this.topTileToY ? Math.round((bounds.bottom - this.topTileFromY) / coef) : Math.round((this.topTileFromY - bounds.top) / coef);
</code></pre>

<p>What does the <code>&lt;</code> in <code>this.topTileFromX &lt;</code> mean?</p>
