var Cart = options.getComponent('Cart');
				var data = {
				fieldId: "custbody_cart",
				type: "string",
				value: "C123456"
			}
			Cart.cancelableOn('afterUpdateLine', function () {
						Cart.setTransactionBodyField(data).then(function()
						{
							debugger;
							console.log(data.fieldId + ' was set to ' + data.value);
						}).fail(function(error)
						{
							debugger;
							console.log('setTransactionBodyField failed.');
						});
			});