diff --git a/data-discovery/src/main/java/webapi/formatfilter/ObscoreExt.java b/data-discovery/src/main/java/webapi/formatfilter/ObscoreExt.java
index 3d46d175f55d867c0e2348284f3db9450ed5f7c2..cec53fc688812177038453512e2e21674497f28b 100644
--- a/data-discovery/src/main/java/webapi/formatfilter/ObscoreExt.java
+++ b/data-discovery/src/main/java/webapi/formatfilter/ObscoreExt.java
@@ -12,12 +12,28 @@ class ObscoreExt
       return colInfo;
    }
 
+   static private ColumnInfo genIntWithNullColInfo(String colLabel, String colDesc)
+   {
+      ColumnInfo colInfo = new ColumnInfo( colLabel, Integer.class,  colDesc );
+      colInfo.setAuxDatum(new DescribedValue(Tables.NULL_VALUE_INFO, Integer.MIN_VALUE));
+      return colInfo;
+   }
+
+
+   static private ColumnInfo genLongWithNullColInfo(String colLabel, String colDesc)
+   {
+      ColumnInfo colInfo = new ColumnInfo( colLabel, Long.class,  colDesc );
+      colInfo.setAuxDatum(new DescribedValue(Tables.NULL_VALUE_INFO, Long.MIN_VALUE));
+      return colInfo;
+   }
+
+
 
    public static final ColumnInfo[] OBSCORE_COLINFO =
    {
 
       new ColumnInfo( "dataproduct_type",  String.class,  "Dataproduct Type (image|cube)" ),
-      new ColumnInfo( "calib_level",       Integer.class, "Calibration level" ),
+      genIntWithNullColInfo("calib_level", "Calibration level" ),
       new ColumnInfo( "obs_collection",    String.class,  "Collection" ),
       new ColumnInfo( "obs_title",         String.class,  "Title" ),
       new ColumnInfo( "obs_id",            String.class,  "Observation Id" ),
@@ -35,25 +51,25 @@ class ObscoreExt
       new ColumnInfo( "s_dec",        Double.class, "Declination" ),
       new ColumnInfo( "s_fov",        Double.class, "Field of view" ),
       new ColumnInfo( "s_region",     String.class, "Region" ),
-      new ColumnInfo( "s_xel1",       Long.class,   "Pixels axis1" ),
-      new ColumnInfo( "s_xel2",       Long.class,   "Pixels axis2" ),
+      genLongWithNullColInfo("s_xel1", "Pixels axis1" ),
+      genLongWithNullColInfo("s_xel2", "Pixels axis2" ),
       new ColumnInfo( "s_resolution", Double.class, "Spatial resolution" ),
 
       new ColumnInfo( "t_min",        Double.class, "Time min" ),
       new ColumnInfo( "t_max",        Double.class, "Time max" ),
       new ColumnInfo( "t_exptime",    Double.class, "Exposure time" ),
       new ColumnInfo( "t_resolution", Double.class, "Time resolution" ),
-      new ColumnInfo( "t_xel",        Long.class,   "Time pixels" ),
+      genLongWithNullColInfo("t_xel", "Time pixels" ),
 
       new ColumnInfo( "em_min",       Double.class, "Spectrum min" ),
       new ColumnInfo( "em_max",       Double.class, "Spectrum max" ),
       new ColumnInfo( "em_res_power", Double.class, "Spectrum resolution power" ),
-      new ColumnInfo( "em_xel",       Long.class,   "Spectrum pixels" ),
+      genLongWithNullColInfo("em_xel", "Spectrum pixels" ),
 
       new ColumnInfo( "o_ucd", String.class, "Observable UCD" ),
 
       new ColumnInfo( "pol_states", String.class, "Polarization states" ),
-      new ColumnInfo( "pol_xel",    Long.class,   "Polarization pixels" ),
+      genLongWithNullColInfo("pol_xel", "Polarization pixels" ),
 
       new ColumnInfo( "facility_name", String.class, "Facility" ),
       new ColumnInfo( "instrument_name", String.class, "Instrument" ),
@@ -112,9 +128,9 @@ class ObscoreExt
 
    public static final ColumnInfo[] VLKB_COLINFO =
    {
-      new ColumnInfo( "overlap",     Integer.class, "Overlap Code" ),
-      new ColumnInfo( "overlapSky",  Integer.class, "Overlap Code for Sky axes" ),
-      new ColumnInfo( "overlapSpec", Integer.class, "Overlap Code for Spectral axis" ),
+      genIntWithNullColInfo("overlap", "Overlap Code" ),
+      genIntWithNullColInfo("overlapSky", "Overlap Code for Sky axes" ),
+      genIntWithNullColInfo("overlapSpec", "Overlap Code for Spectral axis" ),
 
       new ColumnInfo( "s_region_galactic", String.class, "Region [GALACTIC]" ),