if (document.images) {

knopb14_off = new Image(); knopb14_off.src = "../images/knopb14.gif"
knopb14_over = new Image(); knopb14_over.src = "../images/knopb14_over.gif"
knopb15_off = new Image(); knopb15_off.src = "../images/knopb15.gif"
knopb15_over = new Image(); knopb15_over.src = "../images/knopb15_over.gif"
knopb16_off = new Image(); knopb16_off.src = "../images/knopb16.gif"
knopb16_over = new Image(); knopb16_over.src = "../images/knopb16_over.gif"
knopb17_off = new Image(); knopb17_off.src = "../images/knopb17.gif"
knopb17_over = new Image(); knopb17_over.src = "../images/knopb17_over.gif"
knopb18_off = new Image(); knopb18_off.src = "../images/knopb18.gif"
knopb18_over = new Image(); knopb18_over.src = "../images/knopb18_over.gif"
knopb19_off = new Image(); knopb19_off.src = "../images/knopb19.gif"
knopb19_over = new Image(); knopb19_over.src = "../images/knopb19_over.gif"

}

function turn_off(ImageName) {
	if (document.images != null) {
		document[ImageName].src = eval(ImageName + "_off.src");
	}
}

function turn_over(ImageName) {
	if (document.images != null) {
		document[ImageName].src = eval(ImageName + "_over.src");
	}
}