nav_top_off = new Image();
nav_top_off.src="images/navtop_off.gif";
nav_top_on = new Image();
nav_bottom_off = new Image();
nav_bottom_on = new Image();
sub_off = new Image();
sub_on = new Image();

function navigation_on(id) {
    swap_img("navtop"+id,nav_top_on.src,'pagelayer');
    swap_img("navbottom"+id,nav_bottom_on.src,'pagelayer');
}

function navigation_off(id) {
    if (id != current_nav_id) {
	swap_img("navtop"+id,nav_top_off.src,'pagelayer');
	swap_img("navbottom"+id,nav_bottom_off.src,'pagelayer');
    }
}

function subnavigation_on(id) {
    swap_img(id,sub_on.src,'pagelayer');
}

function subnavigation_off(id) {
    if (id != current_sub_id) {
	swap_img(id,sub_off.src,'pagelayer');
    }
}

function swap_img(id,img,layerid) {
    if (is_nav6up || is_ie5up) {
	layerObj = document.getElementById(id);
	layerObj.src=img;
    }  else {
	if (is_nav4) {
	    if (layerid == '' || layerid == undefined) {
		document.images[id].src = img;
	    } else {
		document.layers[layerid].document.images[id].src = img;
	    }
	} else {
	    if (is_ie4up) {
		document.images[id].src = img;
	    }
	}
    }
}

function img_on(navid,layerid) {

    imgid = navid;
    onimg = eval (navid+"_on.src");

    swap_img(imgid,onimg,layerid);
}
function img_off(navid,layerid) {
    
    imgid = navid;
    offimg = eval(navid+"_off.src");
    
    swap_img(imgid,offimg,layerid);
}
function show_layer(id) {
    if (is_nav6up || is_ie5up) {
	layerObj = document.getElementById(id);
	layerObj.style.visibility="visible";
    } else {
	if (is_nav4up) {
	    document.layers[id].visibility = "show";
	} else {
	    if (is_ie4up) {
		document.all[id].style.visibility = "visible";
	    }
	}
    }
}
function hide_layer(id) {
    if (is_nav6up || is_ie5up) {
	layerObj = document.getElementById(id);
	layerObj.style.visibility="hidden";
    } else {
	if (is_nav4up) {
	  document.layers[id].visibility = "hide";
	} else {
	    if (is_ie4up) {
		document.all[id].style.visibility = "hidden";
	    }
	}
    }
}
function set_nav_on() {
    for (i = 1; i < 7;i++) {
	eval("navigation_off(i)");
    }
}

var current_sub_id = "sub1";
var current_nav_id = "1";
var copy_layer='';

function initialise(num) {
    copy_layer_name = 'copy'+num;
    copy_layer = get_copy_layer(copy_layer_name);
    hide_copy_layers();
    show_layer(copy_layer_name);
    set_sub_title(num);
    set_sub_id(num);
    set_nav_id(mynavid);
}
function set_sub_id(num) {
    current_sub_id = "sub"+num;
    for (i = 1; i <= num_sub_nav; i++) {
	subnavigation_off('sub'+i);
    }
    subnavigation_on('sub'+num);
}

function set_sub_title(id) {
    setimg = eval ("subtitle"+id+".src");
    swap_img('subtitle',setimg,'pagelayer');
}
function set_nav_id(id) {
    current_nav_id = id;
    navigation_on(id);
}
function get_copy_layer(id) {
    if (is_dom) {
	copy_layer = document.getElementById(id);
    } else {
	if (is_nav4up) {
	    copy_layer = document.layers[id];
	} else {
	    if (is_ie4up) {
		copy_layer = document.all[id];
	    }
	}
    }
    return copy_layer
}

function hide_copy_layers() {
    for (i=1; i <= num_sub_nav; i++) {
	hide_layer('copy'+i);
    }
}
function open_multimap() {

    golocation = 'http://uk.multimap.com/p/browse.cgi?pc=al54us&GridE=&GridN=&scale=50000&title=How+to+get+to+Fourth+Tier+Solutions+Ltd.&cat=h';

   newWin=window.open(golocation,'external_window','height=400,width=600,menubar,resizable,scrollbars,location');
   newWin.focus();
}