Newer tutorials and proposals use XPath syntax to describe elements and attributes concisely.

SDFormat example:

<model name="model_name">
  <pose>0 0 0.5 0 0 0</pose>
  <link name="link">
  <joint type="revolute" name="my_joint">

SDFormat nested tags and attributes can be represented in XPath syntax. For example, the <model> tag above can be referred to as //model; the name attribute of the <model> tag are referenced as //model/@name; the <link> and <joint>entities within <model> can be referred to as //model/link and //model/joint.