13. In the document structure of claim 12 and wherein: the means for identifying the type and start of the attribute are a start attribute code and an attribute type identifier code in sequence; the means for identifying the type and end of the attribute are an end attribute code and the attribute type identifier code in sequence; and the means for representing the contents of the attribute is a sequence of text codes.
14. In the document structure of claim 13 and wherein: a start attribute code occurring elsewhere in the document structure than at the start of an attribute or an end attribute code occurring elsewhere in the document structure than at the end of an attribute is associates with an unambiguous identity code, whereby the start attribute code or the end attribute code is marked as not beginning or ending an attribute.