这个图源什么情况？

http://skyvector.com/
代码如下：
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<customMultiLayerMapSource>

<name>航图</name>

<tileType>JPG</tileType>

<layers>

<customMapSource>

<name>skyvector</name>

<minZoom>1</minZoom>

<maxZoom>9</maxZoom>

<tileType>JPG</tileType>

<tileUpdate>None</tileUpdate>

<url><![CDATA[http://t{$serverpart}.skyvector.net/tiles/302/1408/1/{$x}/{$y}.jpg]]></url>

<serverParts>0 1</serverParts>

</customMapSource>

<!-- http://t1.skyvector.net/tiles/304/1408/1/642/314.jpg-->

<!-- http://t0.skyvector.net/tiles/301/1408/4/647/312.jpg-->

<!-- http://t0.skyvector.net/tiles/302/1408/3/644/312.jpg-->

</layers>
</customMultiLayerMapSource>
大家帮我看看。