Children and attributes are different. Attributes are like fields to a record. Parent/child is a relation between records. There are clear criteria for choosin

Children and attributes are different. Attributes are like fields to a record. Parent/child is a relation between records. There are clear criteria for choosing attribute vs text representation. Text is for humans; all the rest is for the computer. If we see something like this: <ssn>123</ssn> this means the text is precious and we cannot alter it, only attach some records (‘ssn’) to some character ranges. And in most cases these records need more fields, so we add attrbiutes: ... <date date="2001-01-01">the first day of that year</date> ... This is the usual case in markup: we need the computer to do something with the text and use the records as a guide. But a notational case is different. With notational case we still need the computer to do something, but not about a particular piece of text. (This is actually the general case while text-handling is a specific one.) In this case we can command it directly: <foo> <bar id="a" /> <baz ref="a" /> </foo> There is no text in these records, but we still use notational tools: 1) node type, 2) composition, 3) ordering, 4) naming/referencing. In this case we put everything into attributes. We can have a notational piece with markup parts or a markup part with notational parts, but each has a clear purpose. There is also a third specific case: we want to switch to another notation and in this case we write it as text inside an XML element. SVG is a good example. All data go into attributes, text inside elements appears only when 1) it is a part of the drawing, or 2) we are switching to another notation: <!-- notational --> <svg ...> <!-- switching to CSS, still notational --> <style> ... </style> <!-- markup --> <text>... <tspan class="...">...</tspan> ...</text> <!-- notational again --> <rect ... /> </svg>