… Multiple simultaneous referents:
values in ref

presidents Adams were born in Massachusetts

  Adams, John

  Adams, John Quincy

The ref attribute is used on name-like elements (e.g. persName) and referring strings (rs), as we have discussed previously. The ref attribute can contain multiple values, each separated by a space, which allows you to reference multiple ography entries. So for example, if you have a persName like the one above that references both presidents Adams, you may point to the entries for both John Adams and John Quincy adams. This could also work for instances like rs ref= "#schoenberg #berg #webern"members of the Second Viennese School/rs

Contextual Nuances, slide 7 of 11