PDS_VERSION_ID           = PDS3
RECORD_TYPE             = STREAM
SPACECRAFT_NAME         = "PHOBOS_2"
TARGET_NAME             = "MARS"
OBJECT                  = TEXT
OBJECT                  = TEXT
 INTERCHANGE_FORMAT      = ASCII
 NOTE                    = "ERRATA.TXT for ISM data archive"
 PUBLICATION_DATE        = 2001-04-17
END_OBJECT              = TEXT
END




              Comments on ISM data archive


     This document contains a cumulative set of remarks concerning formatting
errors in the ISM data base.


1.  Data files

All reformatted data files (ie, all data files except telemetry files in the
RAW directory) are formatted using the QUBE object. The QUBE core contains the
data, while the suffix area contains ancillary information (instrumental 
parameters). This information field is actually located before the data field,
and therefore is a prefix rather than a suffix. This organization is not
supported by the PDS, but was originally imposed by the use of SIPS as a
processing tool. The software provided in the data volume can read the data
files with no problem.


2.  Coordinate files

All geographic coordinate files (ie, latitude/longitude) are formatted using
the  QUBE object. In this case, the Qube core is empty and only the suffix
contains  information. Although this is not forbiden by the PDS standard, this
may cause  problems with some software, in particular with ISIS.


3.  Non-conformity to ISIS standard

In data and coordinate files, suffixes items are stored on 2 bytes
(SUFFIX_BYTES = 2) to save space. In the ISIS standard, suffix items should be
stored on 4 bytes. 

In data and coordinate files, record length is 144 bytes. In the ISIS standard,
record length should be 512 bytes. 

In the coordinate files, ISIS does not accept the empty core cube.