Debug attribute group
These attributes are intended to store debugging information during intermediate processing. One possible implementation is to use @xtrf (xml-trace-filename) to store the original source file name through intermediate processing steps, and use @xtrc ( xml-trace-counter) to store an element counter for repositioning authoring tools at the originating element location. If values are assigned in this way in the first stage of a processing stream, values in these attributes can then be used for error recovery.
These attributes are normally hidden from authors and exposed only to processing tools or editor macros. Values used in these attributes might be implementation-dependent.