There can be situations where you don't want a base layer and only want a bunch of layers to work on.
Imagine an online GIS editor where users can add and remove layers but they are not obligated to have an always visible one.
This recipe shows how we can easily avoid the requirement of setting a base layer within the map.
<div id="ch1_avoid_baselayer" style="width: 100%; height: 100%;"></div>
OpenLayers.Mapinstance and set the
// Create the map using the specified DOM element var map = new OpenLayers.Map("ch1_avoid_baselayer", ...