function swaplang () {

	var dir_e = '/eng/';
	var dir_f = '/fra/';

	var file_e = '.html';
	var file_f = 'F.html';

	var curr_page = location.href;
	var next_page = '';

	var test_e = new RegExp(escape(dir_e));
	var test_f = new RegExp(escape(dir_f));

	if (test_e.test(curr_page)) {
		next_page = curr_page.replace(dir_e, dir_f);
		next_page = next_page.replace(file_e, file_f);
		location.href = next_page;
		} else {
	 	if (test_f.test(curr_page)) {
			next_page = curr_page.replace(dir_f, dir_e);
			next_page = next_page.replace(file_f, file_e);
			location.href = next_page;
			} else {
			// no language change required
			}
		}

	}