       &lt;!-- Data type: Integer --&gt;
          &lt;!ATTLIST "TransparentTile" "y" #CDATA #REQUIRED&gt;
            &lt;!-- The tile's Y index --&gt;
            &lt;!-- Data type: Integer --&gt;

      &lt;!ELEMENT "TileOpacities" (OpaqueTile)*&gt;
        &lt;!-- A list of completely opaque tiles --&gt;

        &lt;!ELEMENT "OpaqueTile" EMPTY&gt;
          &lt;!-- The index of a completely opaque tile --&gt;
          &lt;!ATTLIST "OpaqueTile" "x" #CDATA #REQUIRED&gt;
            &lt;!-- The tile's X 