Acronyms as headings in MARC21

[danmichaelo]

Cases like A hasAcronym B can be encoded as

    <datafield tag="150" ind1=" " ind2=" ">
      <subfield code="a">Near earth objects</subfield>
    </datafield>
    <datafield tag="450" ind1=" " ind2=" ">
      <subfield code="a">NEOS</subfield>
      <subfield code="g">d</subfield>
    </datafield>

but what if the acronym is the heading? There's no $g code for that case, so currently we just have to use a normal see reference:

    <datafield tag="150" ind1=" " ind2=" ">
      <subfield code="a">NEOS</subfield>
    </datafield>
    <datafield tag="450" ind1=" " ind2=" ">
      <subfield code="a">Near earth objects</subfield>
    </datafield>