function onlyNumbers() {
	var zero = 48;
	var nine = 57;
	var oEvent = window.event || arguments.callee.caller.arguments[0];
	var key = oEvent.which || oEvent.keyCode;
	if (key < 31)  {
		// caracteres especiales, no cancelar el evento.
	} else if (key >= 37 && key <= 40) {
		// flechas, no cancelar el evento.
	} else if (key < zero || key > nine) {
		if (oEvent.preventDefault) {
			oEvent.preventDefault();
		} else {
			oEvent.returnValue = false;
		}
	}
}
function getObject(id) {
	var oReturn = null;	
	if (document.layers) {                      //NN4+
		oReturn = document.layers[id];
	}
	else if (document.getElementById) {         //gecko(NN6) + IE 5+
		oReturn = document.getElementById(id);
	}
	else if (document.all) {                    //IE 4
		oReturn = document.all[id];
	}
	return oReturn;
}
function getImageName(imagesfolder, product, fv, size) {
	var sReturn;
	sReturn = imagesfolder + "prepaid_" + product + "_" + fv + "_" + size + ".gif";
	return sReturn;
}
function getFaceValue(ctl) {
	var oFV, sId;
	for(i=0; i<5; i++) {
		oFV = null;
		sId = ctl.id + "_" + i;
		oFV = getObject(sId);
		if (oFV != null) {
			if (oFV.checked) {
				var iReturn = parseInt(oFV.value);
				return iReturn;
			}
		}
	}
}
function getProductId(parentControl) {
	var sId = new String(parentControl.id);
	sId = sId.replace("cbxFaceValue", "txtProductId")
	var oInput = getObject(sId);
	if (oInput != null) {
		var iReturn = parseInt(oInput.value);
		return iReturn;
	}
}
function getImageControl(parentControl) {
	var oImg = null;
	var sId = new String(parentControl.id);
	sId = sId.replace("cbxFaceValue", "hypCard")
	var oHyp = getObject(sId);
	if (oHyp != null) {
		oImg = oHyp.firstChild;
		var iFV = getFaceValue(parentControl);
		var iPId = getProductId(parentControl);
		var sHref = "card_detail.aspx?id=" + iPId + "&fv=" + iFV;
		oHyp.href = sHref;
	}
	return oImg;
}