Digression: Just what is XML?
It's a markup language used for annotating text
It is concerned with logical structure
- to identify sections, titles, section headers, chapters, paragraphs,…
It is not concerned with appearance
- you say 'this is a subtitle'not 'this is in bold, 14pt, centered'
- you say 'this is an example'not 'this is in verbatim, indented by 5pts, ragged right'