I think that adding 'sn-' etc. before each id is redundant. I have
an article which has only sections and where all the ids start
with 'sn-'. What is the reason for doing it like that? Can I ommit it?
About the names of the files: is it a convention for doing it like
this: example-tutorial-en.xml? Is there any problem if I do it like
this: example_tutorial_en.xml? (does it break anything, etc.)