============================================
Nagg version 1.6.1 released on 2014-04-01.
============================================

1. Introduction
===============

This document describes the NPP Aggregation tool, nagg, and contains
information on platforms tested, changes since last release and any known
problems.

If you have any questions or comments, please send them to:
    help@hdfgroup.org


2. Platforms Tested
===================
Linux 2.6 32bit and 64bit with gcc 4.1.2, gcc 4.4.7 and icc 13.1.3


3. New features and bug fixes since Version 1.6.0
=================================================
    Configuration
    -------------
    - None

    Features
    --------
    - None

    Bug Fixes
    ---------
    - In version 1.6.0, when a dataset contained exclusively fill values, nagg 
      created null values in a "Data_Products" granule (as defined in CDFCB-X 
      volume I p. 75) instead of valid region references to each corresponding 
      hyperslab in the "All_Data" datasets.  The h5dump output for such a granule 
      will appear as follows:

      ...
      DATASET "/Data_Products/VIIRS-M1-SDR/VIIRS-M1-SDR_Gran_0" {
         DATATYPE  H5T_REFERENCE { H5T_STD_REF_DSETREG }
         DATASPACE  SIMPLE { ( 16 ) / ( H5S_UNLIMITED ) }
         DATA {
            NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
            NULL, NULL, NULL, NULL, NULL, NULL, NULL
         }
      ...

      The data for a granule should not be NULL.  Each granule's DATA should 
      consist of a list of region references such as this:
    
      ...
      DATASET "/Data_Products/VIIRS-M1-SDR/VIIRS-M1-SDR_Gran_0" {
         DATATYPE  H5T_REFERENCE { H5T_STD_REF_DSETREG }
         DATASPACE  SIMPLE { ( 16 ) / ( H5S_UNLIMITED ) }
         DATA {
            DATASET /All_Data/VIIRS-M1-SDR_All/Radiance {(0,0)-(767,3199)},
            DATASET /All_Data/VIIRS-M1-SDR_All/Reflectance {(0,0)-(767,3199)},
            ...
            DATASET /All_Data/VIIRS-M1-SDR_All/ReflectanceFactors {(0)-(1)}
      }
      ...
      
      This version of nagg creates correct region references to the dataset
      region even when no data is stored in the hyperslab.
      (JPSS-86)  LK 20140321

    - If an output file with NULL granule entries as shown above is used as an 
      input file for any previous nagg version, nagg is unable to process the 
      file.  Version 1.6.1 and above will detect this condition and create the
      missing references without writing any data to the target dataset.  
      (JPSS-87)  LK 20140321
    
    - De-aggregating a very large aggregation (129 granules each for 16 VIIRS
      products plus a GEO product) resulted in a nagg failure with too many
      open files on Linux systems.  Open objects were delaying the closing of
      files by H5Fclose().  Debugging code was added to identify the types of
      objects that are open just before H5Fclose() is called.  The open
      objects were identified and properly closed.  nagg now opens 1 input
      file and 17 output files for each output aggregation (of size 1) when
      de-aggregating and unpackaging the file.  The 17 output files are closed
      before opening 17 new files for the next output aggregation.
      (JPSS-91)  LK 20140331

    Limits
    ------
    - See nagg.docx (html, pdf) in the same directory for proposed functionality.
    Current release has the following limitations: 
       * Like (--like) option retrieves three properties (number of granules,
         types contained, and geolocation product or external geolocation file
         attribute) from the example file.  Whether the output should be
         packaged or unpackaged is determined from the geolocation
         characteristics of the example file.  Geolocation only aggregation
         is now supported, but origin and domain are determined only from the
         command line options. 
       * Environment variables or command line options for compliance 
         with file naming convention presume valid types and packaging as
	 defined in the "nagg.h" file.
       * Warnings or failures if granule gaps exceed some threshold are not
         supported.
       * Options to choose repair granule are not supported; for now, the one
         with the latest version is used.
       * Option to replace existing granule with repair granule is not
         supported.  
       * Restrictions on flags and input parameters:
            Directory input is not supported.

      
4. Known problems
=================

    - nagg copies the value of the BeginningOrbitNumber attribute from the
      first granule in an aggregation and the value of the EndingOrbitNumber
      attribute to the attributes in the ..._Aggr dataset for the aggregation.
      If either of those granules are fill granules the value of these 
      attributes may be 0 or a fill value.
    - nagg may fail with a segmentation fault if there is insufficient disk
      drive space to hold the output files.  In general the ouput files will 
      require the same amount of disk space as the input files.