if(document.images) 
{    
  mn1_on = new Image;
  mn1_on.src = 'img/mn1_on.jpg';
  mn1_off = new Image;
  mn1_off.src = 'img/mn1_off.jpg';     

  mn2_on = new Image;
  mn2_on.src = 'img/mn2_on.jpg';
  mn2_off = new Image;
  mn2_off.src = 'img/mn2_off.jpg';     

  mn3_on = new Image;
  mn3_on.src = 'img/mn3_on.jpg';
  mn3_off = new Image;
  mn3_off.src = 'img/mn3_off.jpg';     

  mn4_on = new Image;
  mn4_on.src = 'img/mn4_on.jpg';
  mn4_off = new Image;
  mn4_off.src = 'img/mn4_off.jpg';     

  mn5_on = new Image;
  mn5_on.src = 'img/mn5_on.jpg';
  mn5_off = new Image;
  mn5_off.src = 'img/mn5_off.jpg';     

  mn6_on = new Image;
  mn6_on.src = 'img/mn6_on.jpg';
  mn6_off = new Image;
  mn6_off.src = 'img/mn6_off.jpg';     
}

function imgAct(img_name)
{
  if(document.images) {
    img_on = eval(img_name + '_on.src');      
	  document.getElementById(img_name).src = img_on;
  }
}

function imgInact(img_name)
{
  if(document.images) {
    img_off = eval(img_name + '_off.src');          
    document.getElementById(img_name).src = img_off;
  }
}