if (document.images){
	home_off=new Image
	home_on=new Image
	introduction_off=new Image
	introduction_on=new Image
	themes_off=new Image
	themes_on=new Image
	tour_off=new Image
	tour_on=new Image
	checklist_off=new Image
	checklist_on=new Image
	colophon_off=new Image
	colophon_on=new Image
	section1_off=new Image
	section1_on=new Image
	section2_off=new Image
	section2_on=new Image
	section3_off=new Image
	section3_on=new Image
	section4_off=new Image
	section4_on=new Image
	section5_off=new Image
	section5_on=new Image
		
	home_off.src="images/home_off.gif"
	home_on.src="images/home_on.gif"
	introduction_off.src="images/introduction_off.gif"
	introduction_on.src="images/introduction_on.gif"
	themes_off.src="images/themes_off.gif"
	themes_on.src="images/themes_on.gif"
	tour_off.src="images/tour_off.gif"
	tour_on.src="images/tour_on.gif"
	checklist_off.src="images/checklist_off.gif"
	checklist_on.src="images/checklist_on.gif"
	colophon_off.src="images/colophon_off.gif"
	colophon_on.src="images/colophon_on.gif"
	section1_off.src="images/index/section1_off.gif"
	section1_on.src="images/index/section1_on.gif"
	section2_off.src="images/index/section2_off.gif"
	section2_on.src="images/index/section2_on.gif"
	section3_off.src="images/index/section3_off.gif"
	section3_on.src="images/index/section3_on.gif"
	section4_off.src="images/index/section4_off.gif"
	section4_on.src="images/index/section4_on.gif"
	section5_off.src="images/index/section5_off.gif"
	section5_on.src="images/index/section5_on.gif"
	
	
}

function chgImg(imgField,newImg){
	if (document.images){
		document[imgField].src=eval(newImg+".src")
	}
	
}