FWIW, I searched a small subset of the catalogues we harvest, and
found three that use this pattern. Each consistently used the $0 to
identify the author rather than the work. The order wasn't considered
significant either. Here's an example from each;

    <marc:datafield tag="600" ind1="1" ind2="0">
      <marc:subfield code="a">Minkowski, H.</marc:subfield>
      <marc:subfield code="q">(Hermann),</marc:subfield>
      <marc:subfield code="d">1864-1909.</marc:subfield>
      <marc:subfield code="t">Raum und Zeit.</marc:subfield>
      <marc:subfield
code="0">http://id.loc.gov/authorities/names/n86856296</marc:subfield>
    </marc:datafield>

    <datafield tag="600" ind1="1" ind2="0">
      <subfield code="a">Baum, L. Frank</subfield>
      <subfield code="q">(Lyman Frank),</subfield>
      <subfield code="d">1856-1919.</subfield>
      <subfield code="t">Wizard of Oz</subfield>
      <subfield code="0">(DLC)n 81036429</subfield>
      <subfield code="v">Adaptations.</subfield>
      <subfield code="0">(DLC)sh2002012498</subfield>
    </datafield>

    <datafield tag="600" ind2="0" ind1="0">
      <subfield code="a">Plutarch.</subfield>
      <subfield code="t">Alcibiades.</subfield>
      <subfield
code="0">http://id.loc.gov/authorities/names/nr2006006223</subfield>
      <subfield
code="0">http://viaf.org/viaf/sourceID/LC|nr2006006223</subfield>
    </datafield>