The current attributes and their meaning are shown below.
#FeatureId
Temporary unique ID assigned to this station.
DATA_DATE-
The date when this information was retrieved from the NGS database.
DATA_SRCE-
Data Source where the information for the mark came from.
You should use this link to obtain a full datasheet for the mark
or obtain the datasheets from <http://www.ngs.noaa.gov/cgi-bin/datasheet.prl>
if you intend to use the data for survey control.
DEC_LONG-
Decimal equivalent of the LONGITUDE
Always displayed to 10 decimal places, but you should
see POS_SRCE and POS_ORDER to determine the true accuracy.
DEC_LAT-
Decimal equivalent of the LATITUDE
PID-
Permanent Identifier assigned by NGS to each mark
NAME-
Station Name (a.k.a. Designation)
STATE-
State Code
COUNTY-
County Name
QUAD-
USGS Topographic Quad Map Name
LATITUDE-
Latitude in Deg-Min-Sec format
LONGITUDE-
Longitude in Deg-Min-Sec format
POS_DATUM-
Datum of the LATITUDE,LONGITUDE
Should always be NAD83
DATUM_TAG-
Datum Tag of the LATITUDE,LONGITUDE
NAD83 (1986) indicates positions on the NAD83 datum for the
North American Adjustment, completed in 1986.
NAD83 (nnnn) indicates positions on the NAD83 datum for the
North American Adjustment, but readjusted to a State High
Accuracy Reference Network (HARN) on the date shown in (nnnn).
NAD83 (CORS) indicates positions which are part of the CORS
network.
POS_SRCE-
Position Source for the LATITUDE,LONGITUDE
ADJUSTED = Least squares adjustment.
(Lat,Lon Rounded to 5 decimal places.)
HD_HELD1 = Differentially corrected hand held GPS observations.
(Lat,Lon Rounded to 2 decimal places.)
HD_HELD2 = Autonomous hand held GPS observations.
(Lat,Lon Rounded to 1 decimal places.)
SCALED = Scaled from a topographic map.
(Lat,Lon Rounded to 0 decimal places.)
ELEVATION-
Present if available.
The Orthometric Height in METERS indicating the height above the Geoid.
ELEV_DATUM-
Datum of the ELEVATION
ELEV_SRCE-
Elevation Source for the ELEVATION
ADJUSTED = Direct Digital Output from Least Squares Adjustment
of Precise Leveling.
(Rounded to 3 decimal places.)
ADJ UNCH = Manually Entered (and NOT verified) Output of
Least Squares Adjustment of Precise Leveling.
(Rounded to 3 decimal places.)
POSTED = Pre-1991 Precise Leveling Adjusted to
the NAVD 88 Network After Completion of
the NAVD 88 General Adjustment of 1991.
(Rounded to 3 decimal places.)
READJUST = Precise Leveling Readjusted as Required
by Crustal Motion or Other Cause.
(Rounded to 2 decimal places.)
N HEIGHT = Computed from Precise Leveling Connected
at Only One Published Bench Mark.
(Rounded to 2 decimal places.)
RESET = Reset Computation of Precise Leveling.
(Rounded to 2 decimal places.)
COMPUTED = Computed from Precise Leveling Using
Non-rigorous Adjustment Technique.
(Rounded to 2 decimal places.)
LEVELING = Precise Leveling Performed by Horizontal
Field Party.
(Rounded to 2 decimal places.)
H LEVEL = Level between control points not connected
to bench mark.
(Rounded to 1 decimal places.)
GPS OBS = Computed from GPS Observations.
(Rounded to 1 decimal places.)
VERT ANG = Computed from Vertical Angle Observations.
(Rounded to 1 decimal place;
If No Check, to 0 decimal places.)
SCALED = Scaled from a Topographic Map.
(Rounded to 0 decimal places.)
U HEIGHT = Unvalidated height from precise leveling
connected at only one NSRS point.
(Rounded to 2 decimal places.)
VERTCON = The NAVD 88 height was computed by applying the
VERTCON shift value to the NGVD 29 height.
(Rounded to 0 decimal places.)
ELLIP_HT-
Present if available.
The ellipsoid height in METERS referenced to GRS80 ellipsoid.
ELLIP_SRCE-
Ellipsoid Ht Source for the ELLIP_HT
Should always be GPS_OBS when present.
POS_ORDER-
Order of accuracy for the LATITUDE,LONGITUDE
Should be one of the following-
A,B,1,2,3
Order and class for Orders 1, 2, and 3
are defined in the Federal Geodetic Control Committee publication
"Standards and Specifications for Geodetic Control Networks".
In addition-
Order A stations have a relative accuracy of
5 mm +/- 1-10,000,000 relative to other A-order stations.
Order B stations have a relative accuracy of
8 mm +/- 1- 1,000,000 relative to other A- and B-order stations.
POS_CHECK-
Y=Observational Check was made for the position,
N=NO Observational Check was made for the positions
ELEV_ORDER-
Order of accuracy for the ELEVATION
Should be 1,2, or 3 for Vertical Control Stations.
Will be blank for stations used for Horizontal Control only.
Also see attribute DIST_RATE which is used for some
vertical control stations.
Elevation order and class for 1, 2, and 3
are defined in the Federal Geodetic Control
Committee publication "Standards and Specifications for Geodetic
Control Networks". In addition-
Vertical control which were determined only for the purpose of
supplying a height for Horizontal Distance Reductions are
assigned an order of 3.
Class 0 is used for special cases of
orthometric vertical control as follows-
Vertical Order/Class Tolerance Factor
-------------------- ----------------
1 class 0 2.0 mm or less
2 class 0 8.4 mm or less
3 class 0 12.0 mm or less
ELEV_CLASS-
Should be 0, 1, or 2
See details under ELEV_ORDER
ELEV_CHECK-
Y=Observational Check was made for the orthometric height,
N=NO Observational Check was made for the orthometric heights
VERTCONED-
Y=Orthometric Height was determined by applying VERTCON
to an old NGVD 29 height.
N=Orthometric Height determined by observations.
DIST_RATE-
Distribution rate for POSTED and READJUSTED benchmarks
which do not have an Order and Class are as follows
"Posted bench marks" are vertical control points in the NGS data
base which were excluded from the NAVD 88 general adjustment.
Some of the bench marks were excluded due to large adjustment
residuals, possibly caused by vertical movement of the bench marks
during the time interval between different leveling epochs.
Adjusted NAVD 88 are computed for posted bench marks by
supplemental adjustments.
A range of mean distribution rate corrections is listed for each
posted bench mark in the data portion of the publication.
A summary table of the mean distribution rates and their codes is
listed below. The mean distribution rate corrections which were
applied to the original leveling observations is a good
indication of the usefulness of the posted bench marks' adjusted
NAVD 88 heights.
Distribution Distribution
Rate Code Rate Correction
------------ ---------------
"a" 0.0 thru 1.0 mm/km
"b" 1.1 thru 2.0 "
"c" 2.1 thru 3.0 "
"d" 3.1 thru 4.0 "
"e" 4.1 thru 8.0 "
"f" greater than 8.0 mm/km
POSTED BENCH MARKS SHOULD BE USED WITH CAUTION. As is the case for
all leveling projects, the mandatory FGCS check leveling two-mark or
three-mark tie procedure will usually detect any isolated movement
(or other problem) at an individual bench mark. Of course, regional
movement affecting all the marks equally is not detected by the two-
or three-mark tie procedure.
ELLP_ORDER-
Order of accuracy for the ELLIP_HT
Should be 1,2,3,4, or 5 if present.
The following ellipsoid height order and class relative accuracy
standards have not yet been adopted by the Federal Geodetic
Control Subcommittee, but are currently in use by NGS-
Ellipsoid Height Maximum Height
Classification Difference Accuracy
------------------ -------------------
1 class 1 0.5 (mm)/sqrt(km)
1 class 2 0.7
2 class 1 1.0
2 class 2 1.3
3 class 1 2.0
3 class 2 3.0
4 class 1 6.0
4 class 2 15.0
5 class 1 30.0
5 class 2 60.0
The ellipsoid height difference accuracy (b) is computed from a
a minimally constrained correctly weighted least squares adjustment
by-
b = s / sqrt(d)
where
b = height difference accuracy
s = propagated standard deviation of ellipsoid height
difference in millimeters between control points
obtained from the least squares adjustment.
d = horizontal distance between control points in kilometers
ELLP_class-
Class of accuracy for ELLIP_HT
Should be 1 or 2
See details under ELLP_ORDER
FIRST_RECV-
Date when the station was first monumented
or in the case of landmarks, first observed.
LAST_RECV-
Date when the station was last recovered.
LAST_COND-
Last recovered condition of the mark.
Should be one of the following-
MONUMENTED
FIRST OBSERVED
GOOD
POOR
MARK NOT FOUND
SEE DESCRIPTION
DESTROYED
LAST_RECBY-
Agency who reported the last condition of the mark.
STABILITY-
The stability of the mark may have 1 of 4 codes as indicated below-
A = MOST RELIABLE AND EXPECTED TO HOLD POSITION/ELEVATION WELL
B = PROBABLY HOLD POSITION/ELEVATION WELL
C = MAY HOLD, BUT OF TYPE COMMONLY SUBJECT TO SURFACE MOTION
- E.G. FROST HEAVE, ETC
D = MARK OF QUESTIONABLE OR UNKNOWN STABILITY