The attribute is deprecated. It is recommended to use MediaTrace/media/@ref. This attribute is designed to store xsi:schemaLocation while mediatrace is in micromediatrace form. This value is deprecated in versions after 0.7.76. The attribute describes the type of data expression of the element, such as dt="binary.base64". Specifies the identity of an implementation error associated with the data or block. The value shall be expressed as a implementation check identifer and a version of that implementation check, delimited by a colon.