function showhide(layerID, mode)
{
var currentRef = document.getElementById(layerID).style

modes = new Array
modes[0] = 'none'
modes[1] = 'block'

if(isNaN(mode))
currentRef.display = (currentRef.display == 'none') ? 'block' : 'none'
else
currentRef.display = modes[mode]
}