Q:

KML why are there 3 parts to a coordinate in a point

Having looked at http://dagik.org/kml_intro/E/point.html and KML data I can't seem to figure out what the 0 from 135.2, 35.4, 0. means.
<Placemark> 
 <Point>
  <coordinates>
   135.2, 35.4, 0. 
  </coordinates>
 </Point>
</Placemark>

A:

From the KML Reference:

<coordinates>
(required) A single tuple consisting of floating point
  values for longitude, latitude, and altitude (in that order).
...
Do not include spaces between the three values that describe a coordinate.

