/* Alter other options we want or don't want for restore.  */
if ((*options & EXPORT_BACKUP))
  {
    *options |= (EXPORT_LOCAL_SIGS | EXPORT_ATTRIBUTES
                 | EXPORT_SENSITIVE_REVKEYS);
    *options &= ~(EXPORT_CLEAN | EXPORT_MINIMAL
                  | EXPORT_PKA_FORMAT | EXPORT_DANE_FORMAT);
  }

* Format of the OpenPGP TRUST packet

  According to RFC4880 (5.10), the trust packet (aka ring trust) is
  only used within keyrings and contains data that records the user's
  specifications of which key holds trusted introducers.  The RFC also
  states that the format of this packet is implementation defined and
  SHOULD NOT be emitted to output streams or should be ignored on
  import.  GnuPG uses this packet in several additional ways:

  - 1 octet :: Trust-Value (only used by Subtype SIG)
  - 1 octet :: Signature-Cache (only used by Subtype SIG; value must
               be less than 128)
  - 3 octets :: Fixed value: "gpg"
  - 1 octet  :: Subtype
               - 0 :: Signature cache (SIG)
               - 1 :: Key source on the primary key (KEY)
               - 2 :: Key source on a user id (UID)
  - 1 octet :: Key Source; i.e. the origin of the key:
               - 0 :: Unknown source.
               - 1 :: Public keyserver.
               - 2 :: Preferred keyserver.
               - 3 :: OpenPGP DANE.
               - 4 :: Web Key Directory.
               - 5 :: Import from a trusted URL.
               - 6 :: Import from a trusted file.
               - 7 :: Self generated.
  - 4 octets :: Time of last update.  This is a a four-octet scalar
                with the seconds since Epoch.
  - 1 octet  :: Scalar with the length of the following field.
  - N octets :: String with the URL of the source.  This may be a
                zero-length string.

  If the packets contains only two octets a Subtype of 0 is assumed;
  this is the only format recognized by GnuPG versions < 2.1.18.
  Trust-Value and Signature-Cache must be zero for all subtypes other
  than SIG.

if (rc && (*options & IMPORT_RESTORE))
  {
    /* Alter other options we want or don't want for restore.  */
    *options |= (IMPORT_LOCAL_SIGS | IMPORT_KEEP_OWNERTTRUST);
    *options &= ~(IMPORT_MINIMAL | IMPORT_CLEAN
                  | IMPORT_REPAIR_PKS_SUBKEY_BUG
                  | IMPORT_MERGE_ONLY);
  }