<GiftCertificateSales_Update product_code="test">
<Enabled>Yes|No</Enabled>
<Amount type="sale" />
-- or --
<Amount type="fixed">0.00</Amount>
<NotifyShippingEmail>Yes|No</NotifyShippingEmail>
<NotifyBillingEmail>Yes|No</NotifyBillingEmail>
<EmailAttribute notify="yes|no">attr_code</EmailAttribute>
<DescriptionAttribute>attr_code</DescriptionAttribute>
</GiftCertificateSales_Update>