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Jitter File Product Resources
This document defines the current format of the jitter file products of the Engineering Data Processing System (EDPS). These products are similar to the Observation Logs (Obslogs) produced by the Observation Monitoring System (OMS) that no longer exists. The OMS was replaced because it was too costly to maintain and it was hosted on a platform that is no longer supported at the ST ScI. The EDPS is a less ambitious system that does not attempt to monitor instrument problems. The EDPS jitter files are limited to the engineering data that describes the performance of the Pointing Control System (PCS) including the Fine Guidance Sensors that are used to control the vehicle pointing. The jitter files report on PCS engineering data during the duration of the observation. The old name for these jitter files, observation logs (Obslogs), is now inappropriate, because of the absence of instrument monitoring. However the FITS header and extension formats of the jitter files are not radically different from the original Obslogs. FITS-based tools that access only the PCS related data should be able to handle both the old Obslogs and the new jitter files. The jitter files retain the same file naming conventions as the old obslogs.
One way to distinguish the new jitter files from the old obslogs files is to check the existence of the OPUS_VER keyword (system version id) that replaced the OMS_VER keyword. The EDPS software is part of the larger OPUS system that also supports the Science Data Processing System (SDPS) and the On-the-Fly Reprocessing (OTFR) system. Most of the format changes involve deletions of keywords. Six keywords have been added. There are some improvements in the new files. The accuracy of HST orbit-related statistics has been improved by ignoring the values in the telemetry that must be interpolated. Instead, an orbit model is used to recalculate the orbit position and velocity at the exact time needed. The new jitter files have been generated since mid-February 2003, but there is no specific date since the OMS ran in parallel with EDPS for about a week.
Comparison
The old format is well documented by the Observatory Support Web page maintained by the Telescopes Branch of the Instrument Division. This document is supplemental to the archived Observation Log (jitter file) Documentation.
Changes in image file
There are six new keywords for the jitter image file that has the file extension .jif or .jwf. Keywords that are in the primary header are assigned the extension (Ext) value 0. Keywords in other extensions have the extension value >0 since there can be more than one extension for associated products.
| Keyword | Ext | Comment |
|---|---|---|
| ASN_PTYP | 0 | Association Product Type |
| GSD_FGS | 0 | 1, 2 or 3: FGS ID of dominant FGS |
| GSR_FGS | 0 | 1,2 or 3: FGS ID of subdominant (roll) FGS |
| GS_PRIM | 0 | DOMINANT or ROLL: GS that was acquired first |
| OPUS_VER | 0 | Build version: replaces OMS_VER |
| WCSAXES | >0 | 2: Number of axes for WCS parameters |
There are 43 OMS Obslog keywords that were dropped for the new jitter image file.
| Keyword | Ext | Comment |
|---|---|---|
| OMS_VER | 0 | Replaced by OPUS_VER. OMS is gone. |
| EARTHMOD | 0 | No stray light modeling in EDPS |
| GALACTIC | 0 | Never implemented in OMS |
| MOONMOD | 0 | No stray light modeling in EDPS |
| ZODMOD | 0 | No stray light modeling in EDPS |
| OPERATE | 0 | No SI data in EDPS |
| PRODNAMn | 0 | n=(0..9): unneeded |
| T_ACQ2FL | 0 | Related keyword ACQ2FAIL is gone |
| ACQ2FAIL | >0 | No SI specific data in EDPS |
| T_CLMPER | 0 | Related keyword CLAMPERR is gone |
| CALMPERR | >0 | No SI specific data in EDPS |
| T_DCFUNC | 0 | Related keyword DCFUNCHG is gone |
| DCFUNCHG | >0 | No SI specific data in EDPS |
| T_FGSFAL | 0 | Related keyword FGS_FAIL is gone |
| FGS_FAIL | >0 | Astrometry specific value not supported |
| T_FOSOPN | 0 | Related keyword FOS_OPEN is gone |
| FOS_OPEN | >0 | SI not supported |
| T_FW_ERR | 0 | Related keyword FW_ERROR is gone |
| FW_ERROR | >0 | No SI specific data in EDPS |
| T_HVTOFF | 0 | Related keyword HVOLTOFF is gone |
| HVOLTOFF | >0 | No SI specific data in EDPS |
| T_NO_EPH | 0 | Related keyword NO_EPHEM is gone |
| NO_EPHEM | >0 | EDPS now gets ephemeris from database |
| T_NO_SAM | 0 | Related keyword NO_SAM is gone |
| NO_SAM | >0 | EDPS does not monitor slews |
| T_NOSLEW | 0 | Related keyword NO_SLEW is gone |
| NO_SLEW | >0 | EDPS does not monitor slews |
| T_SISAFE | 0 | Related keyword SI_SAFED is gone |
| SI_SAFED | >0 | No SI specific data in EDPS |
| T_SISPND | 0 | Related keyword SISUSPND is gone |
| SISUSPND | >0 | No SI specific data in EDPS |
| T_TAPDRP | 0 | Related keyword TAPEDROP is gone |
| TAPEDROP | >0 | No tape recorders in HST now |
Changes in table file
The jitter table file that has the file extension .jit or .jwt has very few changes. There are still 28 columns of data in the table. Two of the columns have been replaced. Column 23 has changed from EarhMag, that was an estimate of stray light from the Earth based on a model that is no longer support by EDPS, to BrightLimb, which is a short integer value, where 1 indicated that the limb position closest to the target is bright, and 0 indicates it is dark. Column 24 has changed from SI_Specific, that is not supported by EDPS, to FGS_flags, that provides status data for all three FGS. In addition the comment for the DayNight flag has been corrected. The day value is 1 and the night value is 0. These changes affected the values of the keywords: TTYPE23, TUNIT23, TFORM23, TUNIT24, TTYPE24, and TUNIT24. The value of keyword NAXIS1 changed from 116 to 114 because the size of column 23 change from a four-byte floating value to a two-byte short integer value. The keyword ASN_PTYP was added to the association keywords. It has the same value as that keyword in the image file header.
Changes in association file structure
In the old obslogs, the jitter files for associated exposures were always collected into files with the same filename extension, .jit, .jwt, .jif, or .jwf, as the member exposures. The file name has the association rootname that is found in keyword ASN_ID. Each member exposure provides a FITS extension for a table or image, having the keyword ASN_MTYPE that describes the type of member. The primary header of the association image file has the following keywords updated to reflect statistics for the set of FITS extensions: TSTRTIME, TENDTIME, MGSSPRMS, TNLOSSES, TLOCKLOS, TNREENT, TRECENTR, TV2_RMS, MV2_P2P, TV3_RMS, MV3_P2P, TRA_AVG, TROLLAVG, T_GDACT, T_ACTGSP, T_GSFAIL, T_SGSTAR, T_TLMPRB, T_NOTLM, T_NTMGAP, T_GSGAP, T_SLEWING, and T_TFDDWN. For STIS associations, the wavecal members are separated from the science members by different file extensions: .jwt and .jwf. The structure for STIS associations has not changed. But for NICMOS and ACS, the file rootnames now match the rootnames of the association products. Only the members that are used to generate the association product are collected into FITS extension for that product. The old obslogs used only the association rootname. The new jitter-file associations may have multiple rootnames, ending in 0, 1, 2, etc. The statistical keywords in the primary header listed above are calculated for the subset of members collected for the specific association product. The ACS associations reserve the rootname of the ASN_ID for dithered data combined from multiple positions. At each position, there is an association product having the last character of its rootname being a sequence starting from 1. If there is no dithered product for ACS, the associated exposures at the single position have a product with a rootname ending in 1.
Jitter Image File Header Samples
Here is a sample of a primary header of a jitter image file.
SIMPLE = T / data conform to FITS standard
BITPIX = 32 / bits per data value
NAXIS = 0 / number of data axes
EXTEND = T / File may contain standard extensions
NEXTEND = 1 / Number of standard extensions
GROUPS = F / image is in group format
DATE = '2003-05-20' / date this file was written (yyyy-mm-dd)
FILENAME= 'f63b0104j_jif.fits ' / name of file
FILETYPE= 'JIM ' / type of data found in data file
TELESCOP= 'HST' / telescope used to acquire data
INSTRUME= 'FGS ' / identifier for instrument used to acquire data
EQUINOX = 2000.0 / equinox of celestial coord. system
OPUS_VER= 'OPUS 14.0 ' / OPUS software system version number
PDB_VER = 'CCS ' / Project Database version in use
ROOTNAME= 'f63b0104j ' / rootname of the observation set
TARGNAME= 'ADS14859-3-REF ' / proposer's target name
PROC_TYP= 'NORMAL ' / type of pipeline processing
CONFIG = 'FGS ' / proposed instrument configuration
PROPOSID= 8772 / PEP proposal identifier
PROGRMID= '63B' / program id (base 36)
PARALLEL= 'NO ' / indicates if observation taken in parallel
PRIMESI = 'FGS1 ' / instrument designated as prime
TSTRTIME= '2000.215:14:19:34 ' / Predicted Association Window Start Time
TENDTIME= '2000.215:14:20:57 ' / Predicted Association Window End Time
/ POINTING CONTROL DATA
GUIDECMD= 'FINE LOCK ' / Commanded Guiding mode
GSD_ID = '0316902757' / Dominant Guide Star ID
GSD_RA = 319.411350 / Dominant Guide Star RA (deg)
GSD_DEC = 38.379890 / Dominant Guide Star DEC (deg)
GSD_MAG = 10.743000 / Dominant Guide Star Magnitude
GSD_FGS = '3' / Dominant GS Fine Guidance Sensor Number
GSR_ID = '0316901292' / Roll Guide Star ID
GSR_RA = 319.470520 / Roll Guide Star RA (deg)
GSR_DEC = 38.096450 / Roll Guide Star DEC (deg)
GSR_MAG = 11.746000 / Roll Guide Star Magnitude
GSR_FGS = '2' / Roll GS Fine Guidance Sensor Number
GS_PRIM = 'ROLL ' / Guide star that is primary (dominant or roll)
PREDGSEP= 1034.010 / Predicted Guide Star Separation (arcsec)
MGSSPRMS= 0.1 / maximum Guide Star Separation RMS in assoc.
TNLOSSES= 0 / Number of loss of lock events
TLOCKLOS= 0.000000 / Total loss of lock time
TNRECENT= 0 / Number of recentering events
TRECENTR= 0.000000 / Total recentering time
/ LINE OF SIGHT JITTER SUMMARY
TV2_RMS = 2.5 / total association V2 Axis RMS
MV2_P2P = 18.0 / maximum association V2 Axis peak to peak
TV3_RMS = 2.1 / total association V3 Axis RMS
MV3_P2P = 13.2 / maximum total association V3 Axis peak to peak
TRA_AVG = 319.8427236 / total association Average RA
TDEC_AVG= 38.2369780 / total association Average DEC
TROLLAVG= 7.7885872 / total association Average Roll
T_GDACT = T / Actual guiding mode same for all exposures
T_ACTGSP= T / Actual Guide Star Separation same in all exps.
/ PROBLEM FLAGS and WARNINGS
T_GSFAIL= F / Guide star acquisition failure in any exposure
T_SGSTAR= F / Failed to single star fine lock
T_TLMPRB= F / problem with the engineering telemetry in any e
T_NOTLM = F / no engineering telemetry available in all exps.
T_NTMGAP= 0 / total number of telemetry gaps in association
T_TMGAP = 0.000000 / total duration of missing telemetry in asn. (s)
T_GSGAP = F / missing telemetry during GS acq. in any exp.
T_SLEWNG= F / Slewing occurred during observations
T_TDFDWN= F / Take Data Flag NOT on throughout observations
/ ASSOCIATION KEYWORDS
ASN_ID = 'NONE ' / unique identifier assigned to association
ASN_TAB = 'NONE ' / name of the association table
ASN_MTYP= ' ' / Role of the Member in the Association
ASN_STAT= 'N/A ' / status of association (COMPLETE/INCOMPLETE)
ASN_PROD= F / product created (T/F)
END
Here is the sample image extension for the jitter image file.
XTENSION= 'IMAGE ' / extension type
BITPIX = 32 / bits per data value
NAXIS = 2 / number of data axes
NAXIS1 = 64 / length of first data axis
NAXIS2 = 64 / length of second data axis
PCOUNT = 0 / number of group parameters
GCOUNT = 1 / number of groups
INHERIT = T / inherit the primary header
EXTNAME = 'jit ' / extension name
EXTVER = 1 / extension version number
ROOTNAME= 'f63b0104j ' / rootname of the observation set
EXPNAME = 'f63b0104j ' / exposure identifier
DATAMIN = 0.0 / the minimum value of the data
DATAMAX = 138.0 / the maximum value of the data
ASN_MTYP= ' ' / Role of the Member in the Association
/ World Coordinate System and Related Parameters
WCSAXES = 2 / number of World Coordinate System axes
CRPIX1 = 32.0 / x-coordinate of reference pixel
CRPIX2 = 32.0 / y-coordinate of reference pixel
CRVAL1 = 319.8423281 / first axis value at reference pixel
CRVAL2 = 38.2369176 / second axis value at reference pixel
CTYPE1 = 'RA---TAN' / the coordinate type for the first axis
CTYPE2 = 'DEC--TAN' / the coordinate type for the second axis
CD1_1 = 7.5303224E-08 / partial of first axis coordinate w.r.t. x
CD1_2 = 5.5042838E-07 / partial of first axis coordinate w.r.t. y
CD2_1 = 5.5042838E-07 / partial of second axis coordinate w.r.t. x
CD2_2 = -7.5303224E-08 / partial of second axis coordinate w.r.t. y
/ IMAGE PARAMETERS
COORDSYS= 'FGS1 ' / Image coordinate system
XPIXINC = 2.0 / Plate scale along X in mas per pixel
YPIXINC = 2.0 / Plate scale along Y in mas per pixel
BETA_1 = 0.00 / Angle from +V3 to image +x(toward +V2)
BETA_2 = 90.00 / Angle from +V3 to image +y(toward +V2)
/ OBSERVATION DATA
OBSET_ID= '01' / observation set id
OBSERVTN= '04 ' / observation number (base 36)
PROCTIME= '2003.140:18:36:52 ' / Date-Time When Observation Processed
/ Date-Time Format is YYYY.DDD:HH:MM:SS
STARTIME= '2000.215:14:19:34 ' / Predicted Observation Window Start Time
ENDTIME = '2000.215:14:20:57 ' / Predicted Observation Window End Time
/ SCIENTIFIC INSTRUMENT DATA
TLMFORM = 'FN ' / Telemetry Format
APERTURE= 'FGS1 ' / Aperture
APER_V2 = 720.740 / V2 Aperture position in Vehicle frame (arcsec)
APER_V3 = -7.350 / V3 Aperture position in Vehicle frame (arcsec)
/ SPACECRAFT DATA
ALTITUDE= 585.83 / Average altitude during observation (km)
LOS_SUN = 123.81 / Minimum Line Of Sight to Sun (deg)
LOS_MOON= 125.32 / Minimum Line Of Sight to Moon (deg)
SHADOENT= '2000.215:13:49:29 ' / Earth shadow last entry (predicted)
SHADOEXT= '2000.215:12:46:58 ' / Earth shadow last exit (predicted)
LOS_SCV = 63.94 / Minimum line of sight to S/C veloc. (deg)
LOS_LIMB= 80.5 / Average line of sight to Earth limb (deg)
/ POINTING CONTROL DATA
GUIDEACT= 'FINE LOCK ' / Actual Guiding mode at end of GS acquisition
GSACQ = '2000.215:13:49:49 ' / Actual time of GS Acquisition Completion
ACTGSSEP= 1034.431 / Actual Guide Star Separation (arcsec)
GSSEPRMS= 0.1 / RMS of Guide Star Separation (milli-arcsec)
NLOSSES = 0 / Number of loss of lock events
LOCKLOSS= 0.000000 / Total loss of lock time (sec)
NRECENT = 0 / Number of recentering events (sec)
RECENTR = 0.000000 / Total recentering time
/ LINE OF SIGHT JITTER SUMMARY
V2_RMS = 2.5 / dominant guide star V2 axis RMS (mas)
V2_P2P = 18.0 / dominant guide star V2 axis peak to peak (mas)
V3_RMS = 2.1 / dominant guide star V3 axis RMS (mas)
V3_P2P = 13.2 / dominant guide star V3 axis peak to peak (mas)
RA_AVG = 319.8427236 / Average RA (deg)
DEC_AVG = 38.2369780 / Average DEC (deg)
ROLL_AVG= 7.7885872 / Average Roll (deg)
/ PROBLEM FLAGS and WARNINGS (present only if problem exists)
END
Here is the list of optional keywords.
The first two keywords below occur in the primary header of the jitter image file for STIS target acquisition exposures. The optional keywords in the image extension are used for problem flags. These keywords were not present in the sample headers.
TACXSLEW= / total target acquisition x-slew in SIAS pixels
TACYSLEW= / total target acquisition y-slew in SIAS pixels
/ PROBLEM FLAGS and WARNINGS (present only if problem exists)
GSFAIL = / Guide star acquisition failure
SGSTAR = / Scheduled use of guide star
TLM_PROB= F / problem with the engineering telemetry
NO_TLM = F / no engineering telemetry available for obs.
N_TM_GAP= 0 / number of telemetry gaps during observation
TM_GAP = 0.0 / total duration of missing telemetry (sec.)
GS_GAP = 0.0 / duration of missing tlm. during GS acquisition
SLEWING = F / Slewing occurred during this observation
TDF-DOWN= F / take-data-flag not up during entire exposure
Jitter Table File Header Samples
Here is a sample of a primary header of a jitter table file.
SIMPLE = T / data conform to FITS standard
BITPIX = 32 / bits per data value
NAXIS = 0 / number of data axes
EXTEND = T / File may contain standard extensions
NEXTEND = 1 / Number of standard extensions
GROUPS = F / image is in group format
DATE = '2003-05-20' / date this file was written (yyyy-mm-dd)
FILENAME= 'f63b0104j_jit.fits ' / name of file
FILETYPE= 'JTB ' / type of data found in data file
TELESCOP= 'HST' / telescope used to acquire data
INSTRUME= 'FGS ' / identifier for instrument used to acquire data
EQUINOX = 2000.0 / equinox of celestial coord. system
OPUS_VER= 'OPUS 14.0 ' / OPUS software system version number
PDB_VER = 'CCS ' / Project Database version in use
ROOTNAME= 'f63b0104j ' / rootname of the observation set
TARGNAME= 'ADS14859-3-REF ' / proposer's target name
PROC_TYP= 'NORMAL ' / type of pipeline processing
CONFIG = 'FGS ' / proposed instrument configuration
PROPOSID= 8772 / PEP proposal identifier
PROGRMID= '63B' / program id (base 36)
/ ASSOCIATION KEYWORDS
ASN_ID = 'NONE ' / unique identifier assigned to association
ASN_TAB = 'NONE ' / name of the association table
ASN_MTYP= ' ' / Role of the Member in the Association
END
Here is the sample bintable extension for the jitter table file.
XTENSION= 'BINTABLE' / extension type
BITPIX = 8 / bits per data value
NAXIS = 2 / number of data axes
NAXIS1 = 114 / length of first data axis
NAXIS2 = 28 / length of second data axis
PCOUNT = 0 / number of group parameters
GCOUNT = 1 / number of groups
TFIELDS = 28 / number of fields in each table row
INHERIT = T / inherit the primary header
EXTNAME = 'jit ' / extension name
EXTVER = 1 / extension version number
ROOTNAME= 'f63b0104j ' / rootname of the observation set
EXPNAME = 'f63b0104j ' / exposure identifier
OBSET_ID= '01' / observation set id
PROCTIME= '2003.140:18:36:52 ' / Date-Time When Observation Processed
/ JITTER TABLE COLUMNS
TTYPE1 = 'Seconds ' / three second intervals from start
TUNIT1 = 'seconds ' / units of field 1
TFORM1 = 'E ' / format in which field 1 is coded
TTYPE2 = 'V2_dom ' / dominant FGS V2 coordinate
TUNIT2 = 'arcsec ' / units of field 2
TFORM2 = 'E ' / format in which field 2 is coded
TTYPE3 = 'V3_dom ' / dominant FGS V3 coordinate
TUNIT3 = 'arcsec ' / units of field 3
TFORM3 = 'E ' / format in which field 3 is coded
TTYPE4 = 'V2_roll ' / roll FGS V2 coordinate
TUNIT4 = 'arcsec ' / units of field 4
TFORM4 = 'E ' / format in which field 4 is coded
TTYPE5 = 'V3_roll ' / roll FGS V3 coordinate
TUNIT5 = 'arcsec ' / units of field 5
TFORM5 = 'E ' / format in which field 5 is coded
TTYPE6 = 'SI_V2_AVG ' / mean jitter in V2 over 3 seconds
TUNIT6 = 'arcsec ' / units of field 6
TFORM6 = 'E ' / format in which field 6 is coded
TTYPE7 = 'SI_V2_RMS ' / rms jitter in V2 over 3 seconds
TUNIT7 = 'arcsec ' / units of field 7
TFORM7 = 'E ' / format in which field 7 is coded
TTYPE8 = 'SI_V2_P2P ' / peak jitter in V2 over 3 seconds
TUNIT8 = 'arcsec ' / units of field 8
TFORM8 = 'E ' / format in which field 8 is coded
TTYPE9 = 'SI_V3_AVG ' / mean jitter in V3 over 3 seconds
TUNIT9 = 'arcsec ' / units of field 9
TFORM9 = 'E ' / format in which field 9 is coded
TTYPE10 = 'SI_V3_RMS ' / rms jitter in V3 over 3 seconds
TUNIT10 = 'arcsec ' / units of field 10
TFORM10 = 'E ' / format in which field 10 is coded
TTYPE11 = 'SI_V3_P2P ' / peak jitter in V3 over 3 seconds
TUNIT11 = 'arcsec ' / units of field 11
TFORM11 = 'E ' / format in which field 11 is coded
TTYPE12 = 'RA ' / Right Ascension of aperture reference
TUNIT12 = 'degrees ' / units of field 12
TFORM12 = 'D ' / format in which field 12 is coded
TTYPE13 = 'DEC ' / declination of aperture reference
TUNIT13 = 'degrees ' / units of field 13
TFORM13 = 'D ' / format in which field 13 is coded
TTYPE14 = 'Roll ' / position angle between north and +V3
TUNIT14 = 'degrees ' / units of field 14
TFORM14 = 'D ' / format in which field 14 is coded
TTYPE15 = 'LimbAng ' / angle between V1 axis and Earth limb
TUNIT15 = 'degrees ' / units of field 15
TFORM15 = 'E ' / format in which field 15 is coded
TTYPE16 = 'TermAng ' / angle between V1 axis and terminator
TUNIT16 = 'degrees ' / units of field 16
TFORM16 = 'E ' / format in which field 16 is coded
TTYPE17 = 'LOS_Zenith' / angle between HST zenith and target
TUNIT17 = 'degrees ' / units of field 17
TFORM17 = 'E ' / format in which field 17 is coded
TTYPE18 = 'Latitude ' / HST subpoint latitude
TUNIT18 = 'degrees ' / units of field 18
TFORM18 = 'E ' / format in which field 18 is coded
TTYPE19 = 'Longitude ' / HST subpoint longitude
TUNIT19 = 'degrees ' / units of field 19
TFORM19 = 'E ' / format in which field 19 is coded
TTYPE20 = 'Mag_V1 ' / magnetic field along V1
TUNIT20 = 'Gauss ' / units of field 20
TFORM20 = 'E ' / format in which field 20 is coded
TTYPE21 = 'Mag_V2 ' / magnetic field along V2
TUNIT21 = 'Gauss ' / units of field 21
TFORM21 = 'E ' / format in which field 21 is coded
TTYPE22 = 'Mag_V3 ' / magnetic field along V3
TUNIT22 = 'Gauss ' / units of field 22
TFORM22 = 'E ' / format in which field 22 is coded
TTYPE23 = 'BrightLimb' / Earth limb of LimbAng is bright (1 or 0)
TUNIT23 = ' ' / units of field 23
TFORM23 = 'I ' / format in which field 23 is coded
TTYPE24 = 'FGS_flags ' / FGS status flags
TUNIT24 = ' ' / units of field 24
TFORM24 = 'E ' / format in which field 24 is coded
TTYPE25 = 'DayNight ' / observation taken during day (1) or night (0)
TUNIT25 = ' ' / units of field 25
TFORM25 = 'I ' / format in which field 25 is coded
TTYPE26 = 'Recenter ' / recentering status flag, event in progress = 1
TUNIT26 = ' ' / units of field 26
TFORM26 = 'I ' / format in which field 26 is coded
TTYPE27 = 'TakeData ' / vehicle guiding status, nominal GS tracking = 1
TUNIT27 = ' ' / units of field 27
TFORM27 = 'I ' / format in which field 27 is coded
TTYPE28 = 'SlewFlag ' / vehicle slewing status, slewing = 1
TUNIT28 = ' ' / units of field 28
TFORM28 = 'I ' / format in which field 28 is coded
END