calibration_files/.../*.lblx
- All have lid_references to 
  urn:nasa:pds:context:investigation:mission.new_horizons
  urn:nasa:pds:context:investigation:mission.new_horizons_kem1
Perhaps add another to
  urn:nasa:pds:context:investigation:mission.new_horizons_kem2

calibration_files/inventory.csv
- Please rename this to collection_inventory.csv or even collection.csv

kem2_*/*.lblx
- All have
  <?xml-model href="https://pds.nasa.gov/pds4/img/v1/PDS4_IMG_1J00_1900.sch"
  <?xml-model href="https://pds.nasa.gov/pds4/sp/v1/PDS4_SP_1J00_1320.sch"
    ...
    https://pds.nasa.gov/pds4/img/v1/PDS4_IMG_1J00_1900.xsd"
    https://pds.nasa.gov/pds4/sp/v1/PDS4_SP_1J00_1320.xsd"
but that version doesn't exist. Probably replace those with
  PDS4_IMG_1J00_1890 and PDS4_SP_1J00_1311
- All have
  <nh:detector_name>ALICE spectrograph</nh:detector_name>
  <nh:ALICE_Details>
  </nh:ALICE_Details>
The case is wrong. They should be
  <nh:detector_name>Alice spectrograph</nh:detector_name>
  <nh:Alice_Details>
  </nh:Alice_Details>
- Suggestion: to match the context product's Instrument/name, change
  <name>Alice</name>
to
  <name>ALICE ULTRAVIOLET IMAGING SPECTROGRAPH</name>
- Suggestion: to match the context product's Instrument_Host/name, change
  <name>New Horizons Spacecraft</name>
to
  <name>NEW HORIZONS</name>
- Suggestion: to match the context products' Target/name, change
  <name>Cosmic Background</name>
  <name>Epscma</name>
  <name>Ly-Alpha Field</name>
  <name>Rholeo</name>
  <name>Scattered Ly-Alpha Field</name>
to
  <name>Cosmic Background Radiation</name>
  <name>Epsilon Canis Majoris</name>
  <name>Interstellar Medium</name>
  <name>Rho Leonis</name>
  <name>Interstellar Medium</name>
- 202 labels have
  <Target_Identification>
    <name>Ly-Alpha Field</...>
    <type>Plasma Stream</...>
    <Internal_Reference>
      <lid_reference>urn:nasa:pds:context:target:plasma_stream.interstellar_medium</...>
Should this be a separate context product, i.e. a new LID? 
Lyman-alpha fields seem more specific than interstellar_medium.
- These labels need disp:Display_Direction for PDS4 to know the orientation.

kem2_cal/*.lblx
- Most labels in this directory have a lid_reference to
  urn:nasa:pds:nh_alice:calibration_files:pa_row_of
This LID is unknown. The known LIDs in the calibration_files directory are:
  urn:nasa:pds:nh_alice:calibration_files:pa_wave_002
  urn:nasa:pds:nh_alice:calibration_files:pa_aeff_socc_002
  urn:nasa:pds:nh_alice:calibration_files:pa_wave_45kv_001
  urn:nasa:pds:nh_alice:calibration_files:pa_dark_003a
  urn:nasa:pds:nh_alice:calibration_files:pa_aeff_006
  urn:nasa:pds:nh_alice:calibration_files:pa_dark_002
  urn:nasa:pds:nh_alice:calibration_files:pa_flat_000
  urn:nasa:pds:nh_alice:calibration_files:pa_aeff_007
  urn:nasa:pds:nh_alice:calibration_files:pa_aeff_004
  urn:nasa:pds:nh_alice:calibration_files:pa_aeff_005
  urn:nasa:pds:nh_alice:calibration_files:pa_dark_001
  urn:nasa:pds:nh_alice:calibration_files:pa_aeff_socc_001
  urn:nasa:pds:nh_alice:calibration_files:overview

kem2_*/overview.lblx
- Use https for URLs, so this
  schemaLocation="http://pds.nasa.gov/pds4/pds/v1 http://pds.nasa.gov/pds4/pds/v1/PDS4_PDS_1J00.xsd
should be
  schemaLocation="http://pds.nasa.gov/pds4/pds/v1 https://pds.nasa.gov/pds4/pds/v1/PDS4_PDS_1J00.xsd