Once you have installed Atom, you need to link a plugin that will validate your XML against the guidelines of the Text Encoding Initiative (TEI).
atomic-tei
github repository at https://github.com/neelsmith/atomic-teicd
into the cloned/downloaded repository, and run apm link
That’s it. Note that if you later decide to move the atom-tei
directory somewhere else, you’ll need to rerun apm link
from the new location.