PDS_VERSION_ID          = PDS3
LABEL_REVISION_NOTE     = "2018-10-16 GEO:SHS Added pointer to README.TXT
                           for the PDS4 archive"
RECORD_TYPE             = STREAM
OBJECT                  = TEXT
  PUBLICATION_DATE      = 2015-10-09
  NOTE                  = "AAREADME.TXT describes this volume."
END_OBJECT              = TEXT
END

PLEASE NOTE: This archive has been migrated from PDS3 to PDS4. The
contents and directory structure of the PDS3 archive have not changed, 
but PDS4 metadata in the form of XML files have been added. 
The file README.TXT in the root directory has more information.
The file you are now reading, AAREADME.TXT, was written for the original
PDS3 archive and does not have information about the PDS4 additions.

---- Original contents of AAREADME.TXT are below this line. ----

MESSENGER X-Ray Spectrometer Calibrated Data Archive

Prepared for the Geosciences Discipline Node of the Planetary Data
System

========================================================================
Introduction
========================================================================

This volume contains calibrated (CDR) data and associated documentation 
from the MESSENGER X-Ray Spectrometer (XRS).

A complete description of the design of this volume is given in the XRS
CDR software interface specification. An electronic copy of this
document is located on this volume in the DOCUMENT directory.

This volume is intended for the use of scientists and students in the
study of the geography and geochemistry of the planet Mercury. The data
may be used for research and publication.

========================================================================
Volume Format
========================================================================

All science data are located under the DATA directory. The INDEX              
directory contains a listing of all of the data products included on          
this volume. The CATALOG directory contains PDS documentation describing      
the mission, spacecraft, instrument, and data set. These include:

  CATINFO.TXT                   Description of the CATALOG directory contents
  DATASET.CAT                   XRS calibrated data set description
  INSTRUMENT_HOST.CAT           MESSENGER spacecraft description
  INSTRUMENT.CAT                XRS instrument description
  MISSION.CAT                   MESSENGER mission description
  PERSON.CAT                    MESSENGER mission personnel contact
                                information including XRS personnel,
                                identified as such.
  REF.CAT                       MESSENGER mission reference information,
                                including XRS references.

Additional information on volume organization is given in the CDR SIS
(described above), and in section the 'Volume Contents' below.

========================================================================
File Formats
========================================================================

The data files on this volume are provided in flat IEEE binary format
(extension .DAT). Each data file is also accompanied by a detached PDS label 
file (extension .LBL), an ASCII file containing information describing the 
data file and data record format.

Catalog files (extension .CAT) are provided in ASCII format.

Document files describing the volume and the data are given in HTML and PDF 
formats. 

Text files and detached label files contain ASCII records terminated with
a carriage-return character (ASCII 13) and a line-feed character (ASCII 10).
This format allows the files to be read by MacOS, DOS, UNIX and VMS operating
systems. Note that while both label and catalog files are ASCII, some 
operating systems will not recognize the .LBL and .CAT extensions as ASCII 
types. It may be necessary to either remap these extensions as ASCII in the 
system or text browser, or else to open the files from within the text 
browser.  

========================================================================
Volume Contents
========================================================================

Directory Structure and Contents for XRS CDR Data Archive Volume

The following illustration shows the directory structure overview for the 
XRS CDR archive volume, which bears the PDS-assigned volume id MESSXRS_2001. 
This volume contains the XRS CDR data products, supporting documentation, 
and any additional files required for the volume to be compliant with PDS 
standards. The content of the volume is expected to be updated with periodic 
releases according to the schedule found in the MESSENGER Data Management 
and Archiving Plan (DMAP). Revised CDRs (if needed) will also be 
delivered according to the same schedule. Revised CDRs will have an 
incremented version number in the PDS label.

Directory Structure Overview:


                                <ROOT>
   ________________________________|_____________
   |        |       |        |          |       |
<CALIB> <CATALOG> <DATA> <DOCUMENT>  <INDEX> <LABEL>
                    |_____________________
                    |      |      |      |
                  <2004> <2005> <2006> <2007>
                    |________________________
                    |    |                  |
                  <01> <02>                <12>
                    |______________________________________________
                    |                       |                     |
                  <01>                    <02>                  <31>


Directory Contents:

<ROOT> Directory 
This is the top-level directory of the data volume. The following are files 
contained in the root dirctory.

AAREADME.TXT: (This file) General information file. Provides users with
information about the MESSENGER XRS data products. Directs user to other
documents on the volume containing more detailed information.

ERRATA.TXT: Text file for identifying and describing errors and/or anomalies 
found in the current volume, and possibly previous volumes of a set. Any 
known errors for the associated volume will be documented in this file. This 
includes revised CDRs meant to replace CDRs in a previous PDS delivery.

VOLDESC.CAT: PDS file containing the VOLUME object. This gives a high-level 
description of the contents of the volume.  Information includes: production 
date, producer name and institution, volume ID, etc.


<CALIB> Directory

This directory contains files that describe how the calibration data records
were derived from the experimental data records.

CALINFO.TXT: Description of CALIBRATION directory files.


<CATALOG> Directory

This subdirectory contains the catalog object files for the entire volume. 
The following files are included in the catalog subdirectory.

CATINFO.TXT: Identifies and describes the function of each file in the
catalog directory.

DATASET.CAT: Describes the general content of the data set and includes
information about the duration of the mission and the person or group
responsible for producing the data.

INSTRUMENT.CAT: Describes physical attributes of the XRS instrument and
provides relevant references to published literature.

INSTRUMENT_HOST.CAT: Describes the MESSENGER spacecraft.

MISSION.CAT: Describes the scientific goals and objectives of the MESSENGER 
program. It also identifies key people and institutions.

PERSON.CAT: Lists and provides contact information for the people involved 
in the MESSENGER mission, including those involved with XRS.

REF.CAT: Provides references (reference objects) to scientific papers and     
other publications of interest to those using the data, both for XRS and the  
mission as a whole.


<DATA> Data Directory

This is the top level of the directories containing CDRs.

<DATA/YYYY> Data Directory

Subdirectory of the <DATA> directory for each year.

<DATA/YYYY/MM> Data Directory

Subdirectory of the <DATA/YYYY> directory for each month of the year where
MM ranges from 01 through 12.

<DATA/YYYY/MM/DD> Data Directory

Sub-directores of a <DATA/YYYY/MM> directory, these are the top directories
for the CDR data products. The names of the data directories identify the
day of the month for the start time of the data products contained in
the directories.


<DOCUMENT> Directory

This subdirectory contains the documentation that will be needed in order to 
understand and analyze the CDR data products. Files will be stored in PDF 
and HTML format.

DOCINFO.TXT: Identifies and describes the function of each file in the
DOCUMENT directory.

<DOCUMENT/XRS_CDR_SIS> Subdirectory
XRS_CDR_SIS.LBL: Detached PDS label for XRS_CDR_SIS.PDF and XRS_CDR_SIS.HTM. 

XRS_CDR_SIS.PDF:  The XRS CDR SIS: 'MESSENGER Software Interface
Specification For The X-Ray Spectrometer Calibrated Data Record' in Adobe 
Acrobat format.

XRS_CDR_SIS.HTM:  The XRS CDR SIS: 'MESSENGER Software Interface
Specification For The X-Ray Spectrometer Calibrated Data Record' in HTML 
format.

<DOCUMENT/XRSEDR2CDR> Subdirectory
XRSEDR2CDR.LBL: Detached PDS label for XRSEDR2CDR.PDF and XRSEDR2CDR.HTM.

XRSEDR2CDR.PDF: Description of how the calibration data records were derived
from the experimental data records in Adobe Acrobat format.

XRSEDR2CDR.HTM: Description of how the calibration data records were derived
from the experimental data records in HTML format.


<INDEX> Directory

This subdirectory contains the indices for the XRS CDR data products.
The following files are contained in the index subdirectory.

INDEX.LBL: Detached PDS label for INDEX.TAB.

INDEX.TAB: The CDR index file is organized as a table: there is one entry 
for each of the data files included in the XRS data set; the columns contain 
parameters that describe the observation as well as instrument and 
spacecraft parameters.

INDXINFO.TXT: Identifies and describes the function of each file in the 
index subdirectory.  This includes a description of the structure and
contents of each index table in the subdirectory AND usage notes.

MD5.LBL: Detached PDS label for MD5.TAB.

MD5.TAB: Provides the MD5 checksum (message digest) for each file in the 
archive, with the exception of the MD5.TAB file itself.


<LABEL> Directory

LABINFO.TXT: Identifies and describes the function of each file in the label 
subdirectory.

XRS_CDR.FMT: This format file describes the Binary Table object which stores 
the data in the XRS CDR.

========================================================================
Related PDS Products
========================================================================

The XRS EDR volume (MESSXRS_1001) from which these CDRs were generated is 
available on the PDS website (http://pds.jpl.nasa.gov).

========================================================================
Errata
========================================================================

Every effort has been made to ensure that the data and documentation are      
of the best possible quality. However, all users are encouraged to            
verify the correctness of the data prior to submitting any publications       
or other work based on these data.                                            
                                                                              
The file ERRATA.TXT at the root level of this volume contains a list of       
known deficiencies or caveats associated with data on this volume at the      
time it was published, if any. It also lists  any revisions that have been    
made to the data set as a whole or to individual products.                    
                                                                              
If you find an error on this volume, please report the error to the PDS       
Geosciences Node at geosci@wunder.wustl.edu.

========================================================================
Contacts
========================================================================

For questions concerning these data products and documentation, contact:      
                                                                              
          PDS Geosciences Node                                                
          Washington University                                               
          Dept. of Earth and Planetary Sciences                               
          1 Brookings Drive                                                   
          St. Louis, MO 63130                                                 
          314-935-5493                                                        
                                                                              
          WWW Site:  http://pds-geosciences.wustl.edu                         
          Electronic mail address:  geosci@wunder.wustl.edu                   
                                                                              
                                                                              
For questions regarding PDS Standards or other archive volumes available      
from the PDS, please contact PDS Operator at the PDS Central Node (at         
JPL):                                                                         
                                                                              
                                                                              
    Internet            pds_operator@jpl.nasa.gov                             
    Telephone           (818) 354-4321                                        
    U.S. Mail           Planetary Data System, PDS Operator                   
                        Jet Propulsion Laboratory                             
                        Mail Stop 202-101                                     
                        4800 Oak Grove Dr.                                    
                        Pasadena, CA 91109-8099