I can't get several fields from authority.simple_heading via cstore

The authority.simple_heading table has some cool stuff in it (the thesaurus of an authority record! a sort_value for better sorting!), but it's hard to get to. It's not set up for pcrud access in the IDL. I tried using cstore, but I can only seem to get a handful of fields to access that way. Here are two cstore requests that I attempted:

srfsh# request open-ils.cstore open-ils.cstore.direct.authority.simple_heading.retrieve 6

Received Data: {
  "__c":"ash",
  "__p":[
    6,
    2,
    61,
    "Kabalewski, Dmitri 1904-"
  ]
}

srfsh# request open-ils.cstore open-ils.cstore.direct.authority.simple_heading.retrieve 6, {"select": {"ash":["sort_value","thesaurus"]}}

Received Data: {
  "__c":"ash",
  "__p":[

  ]
}

Is this because the IDL only lists a handful of fields (id, record, atag, value)? It would be great to be able to access sort_value and thesaurus using at least one of Evergreen's APIs! Thanks for your help.