//--------------------------------------------------------------
//
//  Simple Javascript script to reveal/hide selected categories
//
//--------------------------------------------------------------

// Set the visible and hidden variables to the appropriate
// strings for NN and IE.

var lastCategory = null;
var visible;
var hidden;

function initVisibleHidden()
// Initializes the visible and hidden designators.
{
     visible = 'visible';
     hidden = 'hidden';
}

function select ( category )
// Shows/hides the markers in the specified category.
{
  if ( lastCategory == null )
     initVisibleHidden();
  else
     hideCategory( lastCategory);
  showCategory( category );
  lastCategory = category;
}

function showCategory ( category )
// Shows the markers in the specified category.
{
  for ( done=0, j=1; !done; j++ )
  {
     marker = category + j;
     markerSelected = document.getElementById(marker);
     if ( markerSelected != null )
        markerSelected = markerSelected.style;

     if ( markerSelected != null )
       markerSelected.visibility = visible;
     else
       done=1;
  }
}

function hideCategory ( category )
// Hides the markers in the specified category.
{
  for ( done=0, j=1; !done; j++ )
  {
     marker = category + j;
     markerSelected = document.getElementById(marker);
     if ( markerSelected != null )
          markerSelected = markerSelected.style;
     if ( markerSelected != null )
       markerSelected.visibility = hidden;
     else
       done=1;
  }
}