*/
            poFieldDefn = poMainDefn->GetFieldDefn(nIndex);
            m_poDefn->AddFieldDefn(poFieldDefn);
            m_panMainTableFieldMap[nIndex] = m_poDefn->GetFieldCount()-1;
        }
        else if (poRelDefn &&
                 (nIndex=poRelDefn->GetFieldIndex(papszSelectedFields[i]))>=0)
        {
            /* Field from the related table
             */
            poFieldDefn = poRelDefn->GetFieldDefn(nIndex);
            m_poDefn->AddFieldDefn(poFieldDefn);
            m_panRelTableFieldMap[nIndex] = m_poDefn->GetFieldCount()-1;
        }
        else
        {
            // Hummm... field does not exist... likely an unsupported feature!
            // At least send a warning and ignore the field.
            CPLError(CE_Warning, CPLE_IllegalArg,
                     "Selected Field %s not found in source tables %s and %s",
                     papszSelectedFields[i], 
                     poMainDefn->GetName(), poRelDefn->GetName());
        }
    }

    return 0;
}


/**********************************************************************
 *                   TABRelation::CreateRelFields()
 *
 * For write access, create the integer fields in each table that will
 * link them, and setup everything to be ready to write the first feature.
 *
 * This function should be called just before writing the first feature.
 *
 * Returns 0 on success, or -1 or error.
 **********************************************************************/
int  TABRelation::CreateRelFields()
{
    int i;

    /*-----------------------------------------------------------------
     * Create the field in each table.  
     * The default name is "MI_refnum" but if a field with the same name
     * already exists then we'll try to generate a unique name.
     *----------------------------------------------------------------*/
    m_pszMainFieldName = CPLStrdup("MI_Refnum      ");
    strcpy(m_pszMainFieldName, "MI_Refnum");
    i = 1;
    while(m_poDefn->GetFieldIndex(m_pszMainFieldName) >= 0)
    {
        sprintf(m_pszMainFieldName, "MI_Refnum_%d", i++);
    }
    m_pszRelFieldName = CPLStrdup(m_pszMainFieldName);

    m_nMainFieldNo = m_nRelFieldNo = -1;
    if (m_poMainTable->AddFieldNative(m_pszMainFieldName,
                                      TABFInteger, 0, 0) == 0)
        m_nMainFieldNo = m_poMainTable->GetLayerDefn()->GetFieldCount()-1;

    if (m_poRelTable->AddFieldNative(m_pszRelFieldName,
                                     TABFInteger, 0, 0) == 0)
        m_nRelFieldNo = m_poRelTable->GetLayerDefn()->GetFieldCount()-1;

    if (m_nMainFieldNo == -1 || m_nRelFieldNo == -1)
        return -1;

    if (m_poMainTable->SetFieldIndexed(m_nMainFieldNo) == -1)
        return -1;

    if ((m_nRelFieldIndexNo=m_poRelTable->SetFieldIndexed(m_nRelFieldNo)) ==-1)
        return -1;

    m_poRelINDFileRef = m_poRelTable->GetINDFileRef();

    /*-----------------------------------------------------------------
     * Update field maps
     *----------------------------------------------------------------*/
    OGRFeatureDefn *poMainDefn, *poRelDefn;

    poMainDefn = m_poMainTable->GetLayerDefn();
    poRelDefn = m_poRelTable->GetLayerDefn();

    m_panMainTableFieldMap = (int*)CPLRealloc(m_panMainTableFieldMap,
                                      poMainDefn->GetFieldCount()*sizeof(int));
    m_panMainTableFieldMap[poMainDefn->GetFieldCount()-1] = -1;

    m_panRelTableFieldMap = (int*)CPLRealloc(m_panRelTableFieldMap,
                                      poRelDefn->GetFieldCount()*sizeof(int));
    m_panRelTableFieldMap[poRelDefn->GetFieldCount()-1] = -1;

    /*-----------------------------------------------------------------
     * Make sure the first unique field (in poRelTable) is indexed since
     * it is the one against which we will try to match records.
     *----------------------------------------------------------------*/
    if ( m_poRelTable->SetFieldIndexed(0) == -1)
        return -1;

    return 0;
}

/**********************************************************************
 *                   TABRelation::GetFeature()
 *
 * Fill and return a TABFeature object for the specified feature id.
 *
 * The retuned pointer is a new TABFeature that will have to be freed
 * by the caller.
 *
 * Returns NULL if the specified feature id does not exist of if an
 * error happened.  In any case, CPLError() will have been called to
 * report the reason of the failure.
 *
 * __TODO__ The current implementation fetches the features from each table
 * and creates a 3rd feature to merge them.  There would be room for 
 * optimization, at least by avoiding the duplication of the geometry 
 * which can be big sometimes... but this would imply changes at the
 * lower-level in the lib. and we won't go there yet.
 **********************************************************************/
TABFeature *TABRelation::GetFeature(int nFeatureId)
{
    TABFeature *poMainFeature;
    TABFeature *poCurFeature;

    /*-----------------------------------------------------------------
     * Make sure init() has been called
     *----------------------------------------------------------------*/
    if (m_poMainTable == NULL || m_poRelTable == NULL)
    {
        CPLError(CE_Failure, CPLE_IllegalArg,
                 "GetFeatureRef() failed: object not initialized yet!");
        return NULL;
    }

    /*-----------------------------------------------------------------
     * Read main feature and create a new one of the right type
     *----------------------------------------------------------------*/
    if ((poMainFeature = m_poMainTable->GetFeatureRef(nFeatureId)) == NULL)
    {
        // Feature cannot be read from main table... 
        // an error has already been reported.
        return NULL;
    }

    poCurFeature = poMainFeature->CloneTABFeature(m_poDefn);

    /*-----------------------------------------------------------------
     * Keep track of FID and copy the geometry 
     *----------------------------------------------------------------*/
    poCurFeature->SetFID(nFeatureId);

    if (poCurFeature->GetFeatureClass() != TABFCNoGeomFeature)
    {
        OGRGeometry *poGeom;
        poGeom = poMainFeature->GetGeometryRef();
        poCurFeature->SetGeometry(poGeom);
    }

    /*-----------------------------------------------------------------
     * Fetch feature from related table
     *
     * __TODO__ Right now we support only many-to-1 relationships, but
     *          it might be possible to have several related entries
     *          for a single key, and in this case we should return
     *          one new feature for each of them.
     *----------------------------------------------------------------*/
    TABFeature *poRelFeature=NULL;
    GByte *pKey = BuildFieldKey(poMainFeature, m_nMainFieldNo,
                            m_poMainTable->GetNativeFieldType(m_nMainFieldNo),
                                m_nRelFieldIndexNo);
    int i;
    int nRelFeatureId = m_poRelINDFileRef->FindFirst(m_nRelFieldIndexNo, pKey);
    
    if (nRelFeatureId > 0)
        poRelFeature = m_poRelTable->GetFeatureRef(nRelFeatureId);

    /*-----------------------------------------------------------------
     * Copy fields from poMainFeature
     *----------------------------------------------------------------*/
    for(i=0; i<poMainFeature->GetFieldCount(); i++)
    {
        if (m_panMainTableFieldMap[i] != -1)
        {
            poCurFeature->SetField(m_panMainTableFieldMap[i], 
                                     poMainFeature->GetRawFieldRef(i));
        }
    }

    /*-----------------------------------------------------------------
     * Copy fields from poRelFeature...
     *
     * NOTE: For now, if no corresponding feature is found in RelTable
     *       then we will just leave the corresponding fields unset.
     *----------------------------------------------------------------*/
    for(i=0; poRelFeature && i<poRelFeature->GetFieldCount(); i++)
    {
        if (m_panRelTableFieldMap[i] != -1)
        {
            poCurFeature->SetField(m_panRelTableFieldMap[i], 
                                     poRelFeature->GetRawFieldRef(i));
        }
    }

    return poCurFeature;
}



/**********************************************************************
 *                   TABRelation::BuildFieldKey()
 *
 * Return the index key for the specified field in poFeature.
 * Simply maps the call to the proper method in the TABINDFile class.
 *
 * Returns a reference to a TABINDFile internal buffer that should not
 * be freed by the caller.
 **********************************************************************/
GByte *TABRelation::BuildFieldKey(TABFeature *poFeature, int nFieldNo,
                                  TABFieldType eType, int nIndexNo)
{
    GByte *pKey = NULL;

    switch(eType)
    {
      case TABFChar:
        pKey = m_poRelINDFileRef->BuildKey(nIndexNo,
                             poFeature->GetFieldAsString(nFieldNo));
        break;

      case TABFDecimal:
      case TABFFloat:
        pKey = m_poRelINDFileRef->BuildKey(nIndexNo,
                             poFeature->GetFieldAsDouble(nFieldNo));
        break;

      // __TODO__ DateTime fields are 8 bytes long, not supported yet by
      // the indexing code (see bug #1844).
      case TABFDateTime:
        CPLError(CE_Failure, CPLE_NotSupported,
                 "TABRelation on field of type DateTime not supported yet.");
        break;

      case TABFInteger:
      case TABFSmallInt:
      case TABFDate:
      case TABFTime:
      case TABFLogical:
      default:
        pKey = m_poRelINDFileRef->BuildKey(nIndexNo,
                             poFeature->GetFieldAsInteger(nFieldNo));
        break;
    }

    return pKey;
}


/**********************************************************************
 *                   TABRelation::GetNativeFieldType()
 *
 * Returns the native MapInfo field type for the specified field.
 *
 * Returns TABFUnknown if file is not opened, or if specified field index is
 * invalid.
 *
 * Note that field ids are positive and start at 0.
 **********************************************************************/
TABFieldType TABRelation::GetNativeFieldType(int nFieldId)
{
    int i, numFields;

    if (m_poMainTable==NULL || m_poRelTable==NULL ||
        m_panMainTableFieldMap==NULL || m_panRelTableFieldMap==NULL)
        return TABFUnknown;

    /*-----------------------------------------------------------------
     * Look for nFieldId in the field maps and call the corresponding
     * TAB file's GetNativeFieldType()
     *----------------------------------------------------------------*/
    numFields = m_poMainTable->GetLayerDefn()->GetFieldCount();
    for(i=0; i<numFields; i++)
    {
        if (m_panMainTableFieldMap[i] == nFieldId)
        {
            return m_poMainTable->GetNativeFieldType(i);
        }
    }

    numFields = m_poRelTable->GetLayerDefn()->GetFieldCount();
    for(i=0; i<numFields; i++)
    {
        if (m_panRelTableFieldMap[i] == nFieldId)
        {
            return m_poRelTable->GetNativeFieldType(i);
        }
    }

    return TABFUnknown;
}


/**********************************************************************
 *                   TABRelation::AddFieldNative()
 *
 * Create a new field using a native mapinfo data type... this is an 
 * alternative to defining fields through the OGR interface.
 * This function should be called after creating a new dataset, but before 
 * writing the first feature.
 *
 * This function will build/update the OGRFeatureDefn that will have to be
 * used when writing features to this dataset.
 *
 * A reference to the OGRFeatureDefn can be obtained using GetLayerDefn().
 *
 * Returns 0 on success, -1 on error.
 **********************************************************************/
int TABRelation::AddFieldNative(const char *pszName, TABFieldType eMapInfoType,
                                int nWidth /*=0*/, int nPrecision /*=0*/,
                            GBool bIndexed /*=FALSE*/, GBool bUnique/*=FALSE*/)
{
    if (m_poMainTable==NULL || m_poRelTable==NULL ||
        m_panMainTableFieldMap==NULL || m_panRelTableFieldMap==NULL)
        return -1;

    if (!bUnique)
    {
        /*-------------------------------------------------------------
         * Add field to poMainTable and to m_poDefn
         *------------------------------------------------------------*/
        if (m_poMainTable->AddFieldNative(pszName, eMapInfoType,
                                          nWidth, nPrecision,
                                          bIndexed) != 0)
            return -1;

        OGRFeatureDefn *poMainDefn = m_poMainTable->GetLayerDefn();

        m_panMainTableFieldMap = (int*)CPLRealloc(m_panMainTableFieldMap,
                                      poMainDefn->GetFieldCount()*sizeof(int));

        m_poDefn->AddFieldDefn(poMainDefn->GetFieldDefn(poMainDefn->
                                                          GetFieldCount()-1));

        m_panMainTableFieldMap[poMainDefn->GetFieldCount()-1] = 
                                            m_poDefn->GetFieldCount()-1;
    }
    else
    {
        /*-------------------------------------------------------------
         * Add field to poRelTable and to m_poDefn
         *------------------------------------------------------------*/
        if (m_poRelTable->AddFieldNative(pszName, eMapInfoType,
                                         nWidth, nPrecision,
                                         bIndexed) != 0)
            return -1;

        OGRFeatureDefn *poRelDefn = m_poRelTable->GetLayerDefn();

        m_panRelTableFieldMap = (int*)CPLRealloc(m_panRelTableFieldMap,
                                      poRelDefn->GetFieldCount()*sizeof(int));

        m_poDefn->AddFiel