title: What do horizontalAccuracy and verticalAccuracy of a CLLocation refer to?
body: <p>I've been working on a location based app recently and am noticing some strange values for CLLocation. I often get a <code>horizontalAccuracy</code> of <code>1414</code> and a <code>verticalAccuracy</code> of <code>-1</code>. Any clue what this indicates? As far as I can tell, these points are often very accurate. What is the difference between verticalAccuracy and horizontalAccuracy?</p>