// Create a base icon for all of our markers that specifies the
// shadow, icon dimensions, etc.
var baseIcon = new GIcon(G_DEFAULT_ICON);
baseIcon.shadow = "http://www.google.com/mapfiles/shadow50.png";
baseIcon.iconSize = new GSize(20, 34);
baseIcon.shadowSize = new GSize(37, 34);
baseIcon.iconAnchor = new GPoint(9, 34);
baseIcon.infoWindowAnchor = new GPoint(9, 2);

// Creates a marker whose info window displays the letter corresponding
// to the given index.
function createMarker(point, index, details) {
   // Create a lettered icon for this point using our icon class

   var letter = "";
   if (index >= 0) {
      letter = String.fromCharCode("A".charCodeAt(0) + index);
   }
   var letteredIcon = new GIcon(baseIcon);
   letteredIcon.image = "http://www.google.com/mapfiles/marker" + letter + ".png";

   // Set up our GMarkerOptions object
   markerOptions = { icon: letteredIcon };
   var marker = new GMarker(point, markerOptions);

   GEvent.addListener(marker, "click", function() {
      marker.openInfoWindowHtml(details);
   });
   return marker;
}