code: protected Object getFieldData(Integer id, FieldType type, byte[][] fixedData, Var2Data varData)
     {
        Object result = null;
  
        FieldItem item = m_map.get(type);
        if (item != null)
        {
           result = item.read(id, fixedData, varData);
        }
  
        return result;
     }
docs: Retrieve a single field value.
  
  @param id parent entity ID
  @param type field type
  @param fixedData fixed data block
  @param varData var data block
  @return field value