Atom's editor.getGrammar().scopeName

#1

Can I have any description on atom.workspace.getActiveEditor().getGrammar().scopeName ? I’m now working on markdonw-preview package and there is

  if (editor.getGrammar().scopeName !== "source.gfm") {
    console.warn("Cannot render markdown for '" + ((_ref = editor.getUri()) != null ? _ref : 'untitled') + "'");
    return;
  }

and it seems source.gfm means markdown detection.

Thanks.