products_a = new Image();

products_a.src = '/images/button-nav-products-a.gif';

products_b = new Image();

products_b.src = '/images/button-nav-products-b.gif';



industries_a = new Image();

industries_a.src = '/images/button-nav-industries-a.gif';

industries_b = new Image();

industries_b.src = '/images/button-nav-industries-b.gif';



customers_a = new Image();

customers_a.src = '/images/button-nav-customers-a.gif';

customers_b = new Image();

customers_b.src = '/images/button-nav-customers-b.gif';



parts_a = new Image();

parts_a.src = '/images/button-nav-parts-a.gif';

parts_b = new Image();

parts_b.src = '/images/button-nav-parts-b.gif';



library_a = new Image();

library_a.src = '/images/button-nav-library-a.gif';

library_b = new Image();

library_b.src = '/images/button-nav-library-b.gif';



company_a = new Image();

company_a.src = '/images/button-nav-company-a.gif';

company_b = new Image();

company_b.src = '/images/button-nav-company-b.gif';



function fn (name, letter) {

  document[name].src = eval(name + '_' + letter).src;

}