**Number range CHAPTER CALIFORNIA**

**GEOGRAPHIC**

**COORDINATE**

**DATA BASE**

**(GCDB)**

**USERS\'**

**GUIDE**

Bureau of Land Management

California State Office

Branch of Cadastral Survey - GCDB Section

Sacramento, California

916-978-4340

GEOGRAPHIC COORDINATE DATA BASE USERS\' GUIDE

TABLE OF CONTENTS

INTRODUCTION 4

> **The files you will be most interested in** 4

TOWNSHIP NAMING CONVENTIONS 5

ERROR ELLIPSES (GMM) AND RELIABILITIES (PCCS) 5

POINT IDENTIFICATION SYSTEM 5

> SUMMARY 9
>
> Point Identifier Standards 9
>
> Segment Identifiers 9

CONTROL 10

> KEY TO RELIABILITY OF CONTROL POINTS 11

GMM REGIONAL ADJUSTMENT INFORMATION 13

COMPARABLE FILES FOR PCCS AND GMM 15

> C36N01E 16
>
> R36N01E 17
>
> T06N08E.SCR 18
>
> X36N01E 19

TABLE A 20

TABLE B 20

GMM FILES 21

> T06SR20E.CON 21
>
> T06SR20E.CTL 22
>
> T06SR20E.COR 23
>
> T06SR20E.DXF 24
>
> T06SR20E.GEO 25
>
> T06SR20E.LX 26
>
> T06SR20E.PGC 28
>
> T06SR20E.RAW 29
>
> T06SR20E.SID 30
>
> T06SR20E.UTM 31

APPENDIX A - GMM Glossary 32

> ***NO WARRANTY IS MADE BY THE BUREAU OF LAND MANAGEMENT FOR USE OF THE
> DATA FOR PURPOSES NOT INTENDED BY THE BUREAU OF LAND MANAGEMENT.***

November 13, 2023

This page intentionally left blank.

[INTRODUCTION]{.underline}

The Geographic Coordinate Data Base (GCDB) contains the geographic
coordinates, and their associated attributes, for the Public Land Survey
System (PLSS). Coordinates are available for all rectangular corners
down to the 1/16 section corner level, and all special survey corners
(meanders, mining claims, HES, etc).[^1] It provides the foundation for
the BLM\'s Automated Land and Mineral Record System (ALMRS) and will be
useful to anyone trying to attach data to points on the earth\'s
surface. These coordinates were calculated using the most recent survey
information available for a township and control points from various
sources. Two different software packages were used, PLSS Coordinate
Computation System (PCCS) and GCDB Measurement Management (GMM). PCCS
was used first, until May 1993. The file names for the two software
packages are different but the contents are essentially the same.

The PCCS files have coordinates in Latitude/Longitude NAD 27, and
Universal Transverse Mercator projection (UTMs - x,y in meters). State
plane coordinates can be generated if needed. GMM files have coordinates
in all three formats.

**The files you will be most interested in will be:**

> **PCCS - L06N08E, U06N08E, X06N08E**
>
> **GMM - T03SR39E.LX, T03SR39E.UTM, T03SR39E.COR, T03SR39E.DXF,
> T03SR39E.PGC, T03SR39E.GEO, T03SR39E.TPR**

Descriptions of some of the files are included for your information even
though you won\'t be using them. (We know you\'ll be curious.)

You need to know how the point identification system works, the
difference between the meaning of reliability in PCCS versus GMM, and
some information on control points. These topics are discussed below.

The geographic coordinates and their associated products have NO LEGAL
SIGNIFICANCE. They should be used for record keeping, mapping, graphics
and planning purposes only.

We can\'t promise you that the data is flawless. Let us know if you find
any problems. This will help us to improve the quality of the data base.
If you have questions about anything, give us a call. We aim to please!

[TOWNSHIP NAMING CONVENTIONS]{.underline}

BLM has various township naming conventions. They are listed below.

[SURVEY PLATS/NOTES GMM PCCS L FILE ALMRS DED^\*^]{.underline}

T. 22 N., R. 1 W. T22NR01W L22N01W 0220N0010W

T. 14 N., R. 4 E. T14NR04E L14N04E 0140N0040E

T. 11-1/2 S., R. 6 W. T112S06W L11206W 0112S0060W

T. 12 N., R. 24-1/2 E. T12N242E L12N242E 0120N0242E

^\*^ *Data Element Dictionary* [ERROR ELLIPSES (GMM) AND RELIABILITIES
(PCCS)]{.underline}

In GMM, the error region (ellipse) is available, the first value is the
(semi-major) axis of maximum error within the ellipse, and the second
value is the (semi-minor) axis of minimum error within the ellipse. The
values are in feet. The error ellipses are internal to that particular
township only. See Appendix A. They are not a reflection of true
(absolute) coordinate reliability but are relative to each other within
a township reflecting the integrity of the survey information used.

In PCCS, the two values reflect the average and maximum reliability, in
feet, for each point. These values are comparable from one township to
another and are an estimate of the true positional reliability.

[POINT IDENTIFICATION SYSTEM]{.underline}

Point IDs are used to show where in a township a point is located and
generally what kind of point it is (i.e. township exterior, interior,
offset, meander, tract, special survey, mile post). It is a 6 digit
number composed of 2 parts, XxxYyy, related to the x,y axis. In Xxx or
Yyy, X or Y is the line number and xx or yy is the number of
chains[^2]^\*^ from the section corner, going west to east and south to
north. The diagrams on the next 2 pages show how the numbering scheme
works.

Numbers greater than 700700 are reserved for the following special
situations.

Xxx = 711 -799 Boundaries with Mileposts

> 800 -836 Meanders
>
> 837 -899 Tracts
>
> 900 -999 Mineral Surveys, Homestead Entries, etc.

Yyy Numbered sequentially along the survey in increments of 10. The
prefix (Xxx) may be the same for all points in a similar survey.

> In PCCS files, intersections of section lines and special survey lines
> will have two IDs, the \"rectangular\" ([+]{.underline}4) and the
> segment identifier.

![](media/image1.wmf)

**SUMMARY**

**Point Identifier Standards**

**SUMMARY**

**Segment Identifiers**

[CONTROL]{.underline}

Geographic control for GCDB is derived from a variety of sources, the
various sources having a particular reliability. (e.g. Digitized points
from USGS maps have a reliability of 40,40 (feet) whereas NGS first
order points have reliabilities of 1,1 (foot).) The control points are
handled differently by PCCS and GMM. In PCCS the control points are
assigned a reliability and the values for latitude and longitude are
held fixed during the computational process. In GMM the control points
are not held fixed, but are assigned error estimates (weights), and
allowed to adjust during the adjustment process.

In GMM, the published values of control established by NGS and USGS are
assigned error estimates of .001 feet, which is the most accurate the
GMM software allows. In PCCS computed townships, the values for
published control should be identical to the published values. For the
townships computed using GMM the values should be the same to four
decimal places. **YOU ARE ADVISED TO ALWAYS REFER TO THE PUBLISHED
VALUES rather than using the value from the PCCS or GMM files**.

Many of the control points in GCDB are digitized values for PLSS corners
shown as \"found crosses\" on USGS 7-1/2 minute quads. These digitized
points are assigned a reliability of 40,40 (feet) in PCCS or GMM. PCCS
will retain the digitized values during the computation process. GMM
will not retain the digitized values, but will allow the digitized
control to float and will adjust it.

GMM control is assigned an error estimate and provided to the computing
surveyor, the estimate can only be changed where warranted. Some control
is imported from adjacent townships to facilitate the merging of single
township data sets during the regional adjustment. This type of control
is given an error estimate of .001, .001 and is called Merge Control.
For more information on control used during regional processing see page
13. On page 11 is a list of the control reliabilities you\'ll find in
the data files and their possible sources.

We can provide more information on particular control points if you need
it. We have a control data base (in ORACLE software) which contains the
following information on each control point.

> Point ID #, Station Name, Latitude & Longitude in NAD 27,
>
> Elevation in feet (not all points), NGS Order, which USGS Quad it\'s
> on, Source, Township, Range, Section, comments about what it is.

We can query on any of these fields to obtain data.

We also have a Plat and Special Survey data base (in ORACLE software)
which contain the following information about Cadastral Plats.

> Township, Range, BLM District, BLM Resource Area, Forest,
>
> Other (i.e. Indian Reservation, National Park, etc.),
>
> Surveyors, Survey Year, Survey Type, Number of sections, Comments

For Mineral Surveys, HES, etc we also have county, some acreage.

Again, we can query on any of these fields.

Our **SUMMARY Report** includes all the above mentioned data for a
particular township. See the example on page 12.

[KEY TO RELIABILITY OF CONTROL POINTS]{.underline}

[RELIABILITY^1^]{.underline} [SOURCE^2^]{.underline}
[DESCRIPTION]{.underline}

(1,1) NGS From National Geodetic Survey (NGS) tape, 1st order.

(3,3) NGS From NGS Tape, 2nd order.

(10,10) USGS Supplemental Files, or source stated in comments

(1,1) GPSF Forest Service Global Positioning System (GPS)

(1,1) USFS Forest Service

(1,1) G027 Canyon County GPS 1990 (027 is Data Element Dictionary (DED)
code for C.Cnty)

(1,1) GPSU From USGS GPS Project

(1,1) GPSB BLM GPS

(1,1) GPSP Private GPS, D.Evans & Associates work for City of Coeur d\'
Alene 1988.

(10,10) FSC FS Plat conventional tie moving control to a section corner

(10,10) BLMC BLM Plat conventional tie moving control to a section
corner

(16,16) GPSB BLM GPS done with PATHFINDER, good to 16 Feet

(25,25) DOPU USGS Doppler From USGS GPS Project

(25,25) NGS From NGS Tape

(25,25) USGS Supplemental files, USGS-GPS Project, or other

(40,40) MCI Digitized points (found corners) off USGS 7-1/2\' quads.

^1^ (10,10) the average and maximum error, in feet, of the point.

^2^ Source is a code found in the control data base, not in the data
files. If you need more information on a control point we can provide
it.

Summary Report For T. 0360N, R. 0010E, 21 Principal Meridian

Task: 2 25-JUN-92

Complexity: 2

SURVEYOR Year Survey Lotting Source ID #Sec Comments

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- \-\-\-- \-\-\-\-\-\-\-\-\-\-\--
\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-- \-\-\-\--
\-\-\-\-\-\-\-\-\-\-\-\--

HOLMAN ET AL 1870 Original Irregular

MAGEE 1873 Dependent Irregular

BAKER 1882 Dependent Irregular

BERDAN 1882 Dependent Irregular

SANDOW 1882 Dependent Irregular

SANDOW 1882 Original Irregular

GLEAVES 1891 Dependent Irregular

GLEAVES 1891 Original Irregular

GLEAVES 1892 Dependent Irregular

DENT 1908 Dependent Irregular

DENT 1908 Original Irregular

ENGLISH 1922 Dependent Irregular

HIESTER ET AL 1938 Dependent Irregular

SYDLIK ET AL 1957 Dependent Irregular

HAMON ET AL 1983 Dependent Irregular

Special Surveys Sections Number

\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-- \-\-\-\-\--

Mineral 1 2 4547

Min Survey Lode Name

\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

4547 EXCELSIOR PLACER

Quad Name ID \#

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--
\-\-\-\-\-\-\--

Big Bend 41121-A8

Chalk Mountain 40121-H7

Roaring Creek 40121-H8

Skunk Ridge 41121-A7

Base Control Data in Township

Point Latitude Longitude Source Attribute

\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\-\-\--
\-\-\-\-\-\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

100100 405534.1387 1215435.8411 Dig 7.5 or Tie Digtzd BLM method

100300 405719.0499 1215437.0445 Dig 7.5 or Tie Digtzd BLM method

100440 405837.5472 1215437.8898 Dig 7.5 or Tie Digtzd BLM method

100600 405958.0784 1215438.7778 Dig 7.5 or Tie Digtzd BLM method

100700 410050.2440 1215438.5597 Dig 7.5 or Tie Digtzd BLM method

200200 405624.9365 1215329.6398 Dig 7.5 or Tie Digtzd BLM method

200300 405717.3398 1215329.6551 Dig 7.5 or Tie Digtzd BLM method

200400 405812.0896 1215328.2236 Dig 7.5 or Tie Digtzd BLM method

200640 410022.5311 1215329.0548 Dig 7.5 or Tie Digtzd BLM method

300400 405811.9842 1215220.3723 Dig 7.5 or Tie Digtzd BLM method

300700 410050.7404 1215219.3157 Dig 7.5 or Tie Digtzd BLM method

400100 405532.9234 1215113.9848 Dig 7.5 or Tie Digtzd BLM method

GMM REGIONAL ADJUSTMENT INFORMATION

The GMM software allows for the adjustment of blocks of townships. For
administrative purposes these blocks are given the designation Txxa,
where T = Task, xx = number of the task, and a = block of tps. within
task. The number of townships in a block varies.

As of November 9, 1994, in order to maintain seamless edge match between
blocks of townships the edges of blocks may be held rigid. This
procedure will be changed in the future. As of July 16, 1995, edge match
is accomplished by holding the edge of a buffer of townships fixed.
Where buffer townships are one tier of previously processed townships,
adjacent to the region being adjusted. The buffer townships are included
in the adjustment, but the edge is held fixed with the adjacent
townships that are also from the previous adjustment. See the diagram on
page 14. For example, block 1 is adjusted first, block 2 is adjusted
with one tier of from block 1 included and a fixed boundary. Block 3 is
adjusted with one tier from block 1 (includes township that was adjusted
with block 2) and a fixed boundary. Block D is adjusted with one tier
from blocks 1, 2, and 3 and 2 fixed boundaries.

Many of the files for a regional adjustment are the same as those for a
single township adjustment. These files do not exist for the regional
adjustment: \<block\>.RAW, \<block\>.CON, \<block\>.SID, or any of the
files relating to subdivision of sections. This is because the GMM
software assembles the data for a block of townships, from the single
township files into block files. After the regional adjustment is
completed the GMM software is used to update the single township files
with the regional adjustment data. A \<block\>.DXF file may exist which
includes all the townships in a block, but without any section
subdivision.

[Merge Control Points]{.underline}

Control points imported as Merge Control are thrown out during the
merging process. All other control points used in a regional adjustment,
are the same control points as those used for the single township
adjustment. Only the regionally adjusted coordinate are useful.

As of August 1, 1995, the following regions have protracted data
included in them: TASK0, TASK1, TASK2, TASK3, TASK4 and TASK21. Some of
TASK21 and most of TASK22 does not include protracted data. Task 23 does
not include any protracted data. For information on what areas a task
covers, or what the data exists, contact the California GCDB Data
Steward.

COMPARABLE FILES FOR PCCS AND GMM

[PCCS GMM]{.underline}

Bxxx N/A none

Cxxx xxx.CTL

Dxxx N/A none

Fxxx N/A none

Hxxx N/A xxx.CON

Lxxx N/A xxx.LX

Pxxx N/A none

xxx.LL and xxx.QQ xxx.LL and xxx.QQ

Rxxx xxx.RAW

xxx.SCR xxx.DXF

Uxxx N/A xxx.UTM

Xxxx xxx.PGC

Zxxx N/A xxx.SID

none xxx.COR

none xxx.GEO

none xxx.SD

none xxx.SUB

none xxx.INT

none xxx.TPR or xxx.INR

Any files not shown are for use of the software and are only useful to
the GCDB. PCCS files marked N/A are not available.

PCCS C36N01E

Geographic Coordinate File. Could be useful outside GCDB.

TWP 0360 RNG 0010 PM Mnt Diablo California(CA) DATE 05/01/92

ORIGIN 405834.0000 1215135.0000 4000.000 0 0 2000.0000 5000.0000

100100 405534.1387 1215435.8411 4000.000 40 40 1789.6264 4724.2048

100300 405719.0499 1215437.0445 4000.000 40 40 1788.3196 4885.1090

100440 405837.5472 1215437.8898 4000.000 40 40 1787.4067 5005.5022

100600 405958.0784 1215438.7778 4000.000 40 40 1786.4466 5129.0154

100700 410050.2440 1215438.5597 4000.000 40 40 1786.7468 5209.0231

200200 405624.9365 1215329.6398 4000.000 40 40 1866.6672 4802.0777

200300 405717.3398 1215329.6551 4000.000 40 40 1866.6787 4882.4492

200400 405812.0896 1215328.2236 4000.000 40 40 1868.3734 4966.4193

200640 410022.5311 1215329.0548 4000.000 40 40 1867.4797 5166.4808

300400 405811.9842 1215220.3723 4000.000 40 40 1947.2530 4966.2377

400100 405532.9234 1215113.9848 4000.000 40 40 2024.4472 4722.2813

400500 405903.7140 1215110.7006 4000.000 40 40 2028.2428 5045.5741

573700 410049.7263 1214857.5151 4000.000 40 40 2182.9608 5208.2126

600198 405624.8651 1214856.4271 4000.000 40 40 2184.4296 4801.9903

643100 405533.0275 1214817.0702 4000.000 40 40 2230.2540 4722.5126

700100 405532.9005 1214747.1030 4000.000 40 40 2265.1153 4722.3414

700113 405541.8552 1214747.7486 4000.000 100 100 2264.3544 4736.0747

683700 410050.0031 1214749.3533 4000.000 40 40 2262.1487 5208.6854

693700 410057.7226 1214749.3687 4000.000 40 40 2262.1223 5220.5250

700700 410057.7276 1214744.2319 4000.000 100 100 2268.0898 5220.5370

140700 410050.3760 1215403.6100 4000.000 10 10 1827.3502 5209.2041

404700 410049.6960 1215107.4800 4000.000 10 10 2031.9718 5208.1218

\|\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|
\|\-\-\-\-\--\| \|\| \|\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|

1 2 3 4 5 6

1 - Point ID

2 - NAD 27 Latitude/Longitude. The decimal is located after the seconds.

3 - Project elevation in feet.

4 - Average Minimum Reliability in feet.

5 - Maximum Reliability in feet. (Control points have equal ave/max.)

6 - (X,Y) Cartesian tangent plane coordinates in chains unit. Origin is
at Point ID 400400 or near the center of the township which is assigned
a false departure of 2000 chs. and latitude of 5000 chs.

Description:

Contains all the available control for a township. Not all of the
control will necessarily be used. The control resides in the GCDB
Control Data Base.

PCCS R36N01E

Raw Data File. Only useful to GCDB.

TWP 0360 RNG 0010 PM Mnt Diablo California(CA) DATE 05/01/92

999999

700100 700113 14.700 1 4400. 1908

700113 700120 5.360 1 5000. 1908

700120 700133 14.730 1 5000. 1908

700133 700140 5.330 1 5000. 1908

700140 700153 14.760 1 2500. 1908

700153 700160 5.345 1 0. 1908

700160 700193 14.730 1 0. 1908

700193 700200 5.375 1 0. 1908

700200 700213 14.700 1 0. 1892

700213 700220 5.300 1 0. 1892

700220 700240 20.000 1 0. PROTRCTION

*and then further down in the file\....*

700100 667100 11.966 4 892800. 1908

667100 660100 8.319 4 892800. 1908

660100 643100 14.535 4 892800. 1908

643100 640100 5.750 4 894200. 1908

640100 623100 15.455 4 900000. 1908

623100 620100 3.985 4 900000. 1908

620100 603100 17.220 4 900000. 1908

603100 600100 2.780 4 900000. 1908

600100 563100 16.685 4 900000. 1892

563100 543100 19.465 4 900000. 1892

\|\-\-\-\-\-\-\-\-\-\-\-\--\| \|\-\-\--\| \| \|\-\-\-\--\| \|\--\|

1 2 3 4 5

1 - From and to station Point IDs.

2 - Horizontal distance in chains.

3 - Bearing quadrant ( 1=NE, 2=SE, 3=SW, 4=NW)

4 - Bearing in degrees, minutes, and seconds. The decimal is located
after the seconds. The first example shows 5 minutes, the last shows 90
degrees.

5 - [Source Identifier number (SID)]{.underline} Each data source,
whether it is an official cadastral survey plat, state or local survey
plat, deeds, etc., utilized in generating coordinates for the GCDB, will
be assigned a unique SID number.

Description:

This is the raw data on which PCCS performs it computations. It is
abstracted from the survey records and entered into PCCS.

PCCS T06N08E.SCR

Script File. For use in AutoCAD.

layer

new

twp,sect,int,annot,points

color

magenta

twp

color

blue

sect

color

green

int

*and further down in the file\.....*

layer

set

sect

pline

0.61534236000E+06,0.48512767700E+07

0.61533369000E+06,0.48516727400E+07

0.61532502000E+06,0.48520687000E+07

0.61531634000E+06,0.48524646700E+07

0.61530767000E+06,0.48528606400E+07

0.61530015000E+06,0.48532574500E+07

0.61529263000E+06,0.48536542700E+07

0.61528511000E+06,0.48540510800E+07

0.61527759000E+06,0.48544479000E+07

0.61527007000E+06,0.48548447100E+07

0.61526255000E+06,0.48552415200E+07

0.61525502000E+06,0.48556383400E+07

0.61524750000E+06,0.48560351500E+07

Description:

AutoCAD script files are created from PCCS Lxx files. They can then be
brought into AutoCAD to generate a drawing of the township.

PCCS X36N01E

Geographic Coordinate File. Only useful to GCDB.

TWP 36N RNG 01E PM Mnt Diablo California(CA) DATE 06/11/92

ORIGIN 405834.0000 1215135.0000 4000.000 0 0 2000.0000 5000.0000

100100 405534.1387 1215435.8411 4000.000 40 40 1789.6264 4724.2048

100120 405547.2527 1215435.9914 4000.000 154 363 1789.4630 4744.3178

100140 405600.3666 1215436.1420 4000.000 153 363 1789.2996 4764.4309

100160 405613.4806 1215436.2923 4000.000 154 363 1789.1362 4784.5439

100200 405626.5944 1215436.4428 4000.000 153 363 1788.9729 4804.6570

100220 405639.7084 1215436.5932 4000.000 153 363 1788.8095 4824.7700

100240 405652.8222 1215436.7437 4000.000 153 363 1788.6461 4844.8830

100260 405705.9361 1215436.8940 4000.000 153 363 1788.4829 4864.9960

100300 405719.0499 1215437.0445 4000.000 40 40 1788.3196 4885.1090

100320 405732.1328 1215437.1853 4000.000 154 363 1788.1674 4905.1745

100340 405745.2157 1215437.3263 4000.000 153 363 1788.0152 4925.2401

100360 405758.2986 1215437.4671 4000.000 154 363 1787.8630 4945.3056

100400 405811.3815 1215437.6080 4000.000 153 363 1787.7109 4965.3712

100420 405824.4644 1215437.7488 4000.000 153 363 1787.5588 4985.4367

100440 405837.5472 1215437.8898 4000.000 40 40 1787.4067 5005.5022

100460 405850.9691 1215438.0377 4000.000 153 363 1787.2467 5026.0878

100500 405904.3910 1215438.1858 4000.000 153 363 1787.0866 5046.6733

100520 405917.8128 1215438.3338 4000.000 153 363 1786.9265 5067.2588

100540 405931.2347 1215438.4818 4000.000 153 363 1786.7665 5087.8443

100560 405944.6565 1215438.6298 4000.000 153 363 1786.6065 5108.4298

100600 405958.0784 1215438.7778 4000.000 40 40 1786.4466 5129.0154

100620 410011.3044 1215438.9352 4000.000 154 363 1786.2755 5149.3006

100640 410024.5305 1215439.0927 4000.000 12 35 1786.1045 5169.5859

100660 410037.3873 1215438.8262 4000.000 153 363 1786.4256 5189.3045

100700 410050.2440 1215438.5597 4000.000 40 40 1786.7468 5209.0231

113100 405534.0717 1215424.7054 4000.000 153 363 1802.5806 4724.0949

120100 405534.0374 1215419.0198 4000.000 153 363 1809.1947 4724.0387

120120 405547.0734 1215419.1658 4000.000 154 363 1809.0352 4744.0321

120140 405600.1087 1215419.3119 4000.000 154 363 1808.8757 4764.0246

120160 405613.1429 1215419.4582 4000.000 154 363 1808.7159 4784.0154

120200 405626.1765 1215419.6046 4000.000 158 429 1808.5562 4804.0053

120220 405639.2876 1215419.7086 4000.000 158 429 1808.4456 4824.1139

120240 405652.3983 1215419.8128 4000.000 158 429 1808.3351 4844.2220

120260 405705.5083 1215419.9168 4000.000 158 429 1808.2246 4864.3290

120300 405718.6179 1215420.0209 4000.000 158 429 1808.1142 4884.4355

120320 405731.8552 1215420.1064 4000.000 154 363 1808.0254 4904.7378

\|\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|
\|\-\-\-\-\--\| \|-\| \|-\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|

1 2 3 4 5 6

1 - Point ID

2 - NAD 27 Latitude/Longitude. The decimal is located after the seconds.

3 - Project elevation in feet.

4 - Average Minimum Reliability in feet.

5 - Maximum Reliability in feet. (Control points have equal ave/max.)

6 - (X,Y) Cartesian tangent plane coordinates in chains unit. Origin is
at Point ID 400400 or a point near the center of the township which is
assigned a false departure of 2000 chs. and latitude of 5000 chs.

Description:

Contains the above described values for every PCCS point in the
township, including sixteenths and special surveys.

TABLE A

**[SOURCE AGENC]{.underline}Y**: (3-6 characters) Generally, this will
be a three letter abbreviation for the agency which created the
document. Below are some examples. If other agencies are needed, contact
the BLM.

BLM Bureau of Land Management - 1946 to present

GLO General Land Office - pre 1946

BOR Bureau of Reclamation

CGS Coast and Geodetic Survey

NGS National Geodetic Survey

USC&GS US Coast & Geological Survey

USCE US Corp of Engineers

USGS US Geological Survey

USFS US Forest Office

NPS National Park Services

DMA Defense Mapping Agency

FAA Federal Aviation Administration

CALT California Dept. of Transportation

NOAA National Oceanic & Atmosphere Administration

LAWP Los Angeles Water and Power

MWD Metropolitan Water District

CAnn Local Agency Codes for California from the Data Element Dictionary,
Appendix A.

For countries other than the USA, use the first three letters.

TABLE B

**[SURVEY TYPE]{.underline}:** (1 character) This attribute describes
the method or procedure used to determine the measurement value for a
line. It is possible that one .SID may relate to several of these survey
types. Select the one that best describes the record.

+--------------------------------+---+--------------------------------+
| A LOCATION SURVEY              |   | K SUPPLEMENTAL PLAT            |
|                                |   |                                |
| B RETRACEMENT SURVEY           |   | M INTERNATIONAL BOUNDARY       |
|                                |   |                                |
| C CORRECTIVE RESURVEY          |   | N NO SURVEY PLAT, MAP ONLY     |
|                                |   |                                |
| D DEPENDENT RESURVEY           |   | O ORIGINAL SURVEY              |
|                                |   |                                |
| E ACQUIRED LANDS SURVEY        |   | P PROTRACTION DIAGRAM          |
|                                |   |                                |
| F OMITTED LANDS SURVEYS        |   | Q EXCHANGE SURVEY              |
|                                |   |                                |
| I INDEPENDENT RESURVEY         |   | R SEGREGATION SURVEY           |
|                                |   |                                |
| J OTHER                        |   | Z UNKNOWN                      |
+--------------------------------+---+--------------------------------+

GMM FILES T06SR20E.CON

Geographic Coordinate File. Only useful to GCDB.

TWP 0060 RNG 0200 PM Mnt Diablo California(CA) DATE 11/29/93

ORIGIN 382203.0000 1194647.0000 4000.000 0 0 2000.0000 5000.0000

100600 382307.7693 1194931.8103 7000.000 40 40

200640 382332.7680 1194828.7847 7000.000 40 40

240700 382400.8530 1194755.8351 7000.000 40 40

400240 382018.8930 1194629.4619 7000.000 40 40

540100 381904.6360 1194447.6905 7000.000 40 40

673700 382400.8530 1194308.4194 7000.000 100 100

700100 381902.9946 1194311.0783 7000.000 100 100

700700 382400.8530 1194303.3975 7000.000 100 100

\|\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|
\|\-\-\-\-\--\| \|\-\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|

1 2 3 4 5

1 - Point ID

2 - NAD 27 Latitude/Longitude. The decimal is located after the seconds.

3 - Project elevation in feet.

4 - Error estimates in feet.

5 - These are meaningless values.

Description:

This file contains all the control used in the township.

GMM T06SR20E.CTL

Geographic Coordinate File. Only useful to GCDB.

TWP 0060 RNG 0200 PM Mnt Diablo California(CA) DATE 11/29/93

ORIGIN 382203.0000 1194647.0000 4000.000 0 0 2000.0000 5000.0000

100100 381903.0022 1194947.6793 4000.000 283 283 1781.7713 4724.1200

100100 381903.0090 1194948.0308 4000.000 100 100 1781.3468 4724.1306

100600 382307.7693 1194931.8103 4000.000 40 40 1801.1243 5099.3422

100700 382359.9451 1194931.8103 4000.000 100 100 1801.1640 5179.3292

117100 381902.8935 1194930.9747 4000.000 57 57 1801.9475 4723.9429

117100 381902.9410 1194931.5416 4000.000 100 100 1801.2628 4724.0160

200640 382332.7680 1194828.7847 4000.000 40 40 1877.1887 5137.6354

240700 382400.8530 1194755.8351 4000.000 40 40 1916.9539 5180.6803

400240 382018.8930 1194629.4619 4000.000 40 40 2021.1768 4840.4027

540100 381904.6360 1194447.6905 4000.000 40 40 2144.1039 4726.5912

673700 382400.8530 1194308.4194 4000.000 100 100 2263.7064 5180.7585

700100 381902.9946 1194311.0783 4000.000 100 100 2260.7952 4724.1337

700700 382400.8530 1194303.3975 4000.000 100 100 2269.7651 5180.7625

\|\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|
\|\-\-\-\-\--\| \|\-\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|

1 2 3 4 5

1 - Point ID

2 - NAD 27 Latitude/Longitude. The decimal is located after the seconds.

3 - Project elevation in feet.

4 - Error estimates in feet.

5 - (X,Y) Cartesian tangent plane coordinates in chains unit. Origin is
assigned a false departure of 2000 chs. and latitude of 5000 chs.

Description:

This is a backup control file. It contains all the control available in
the township but does not include transferred points.

GMM T06SR20E.COR

Coordinate File. Useful to State Plane Coordinate users.

100100 2622610.193 244477.950

100200 2622538.727 249720.785

100300 2622665.686 254734.966

100320 2622710.389 255952.257

100340 2622755.095 257169.537

100363 2622799.793 258386.817

100383 2622844.492 259604.098

100400 2622863.104 260523.291

100403 2622860.824 260850.571

100423 2622922.320 262200.202

100443 2622983.814 263549.823

100463 2623045.306 264899.445

100500 2623043.731 265271.658

100513 2623059.312 266086.242

100540 2623094.754 267150.628

100560 2623130.200 268215.014

100600 2623165.641 269279.390

100640 2623044.672 271936.176

100660 2622998.748 273259.782

100700 2622952.826 274583.377

\|\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|

1 2

1 - Point ID.

2 - State Plane Coordinates (x,y) easting & northing in feet and NAD 27.

Description:

These are the State Plane coordinates for the township. GMM does all its
computations in SPCs and then converts them into UTMs and Lat/Long.

GMM T06SR20E.DXF

Line Data File for CAD (Computer Aided Design) packages and other
software. For CAD users.

0

SECTION

2

HEADER

9

\$ACADVER

1

AC1004

9

\$INSBASE

10

0.0

*and then to the end of the file\.....*

1

N90- 0W

50

0.13

0

ENDSEC

0

EOF

Description:

This drawing interchange file can be brought into many software packages
to produce a drawing of the township.

GMM T06SR20E.GEO

Geographic Coordinate File. For those who need only latitude & longitude
of points.

100100 38-19- 3.17160 119-49- 47.46953

100200 38-19- 55.00114 119-49- 46.79509

100300 38-20- 44.52412 119-49- 43.69914

100320 38-20- 56.54346 119-49- 42.77309

100340 38-21- 8.56279 119-49- 41.84701

100363 38-21- 20.58211 119-49- 40.92089

100383 38-21- 32.60141 119-49- 39.99472

100400 38-21- 41.68105 119-49- 39.48527

100403 38-21- 44.91592 119-49- 39.41571

100423 38-21- 58.23917 119-49- 38.23878

100443 38-22- 11.56242 119-49- 37.06179

100463 38-22- 24.88563 119-49- 35.88475

100500 38-22- 28.56438 119-49- 35.79272

100513 38-22- 36.61094 119-49- 35.35251

100540 38-22- 47.12141 119-49- 34.58787

100560 38-22- 57.63186 119-49- 33.82319

100600 38-23- 8.14230 119-49- 33.05850

100640 38-23- 34.42685 119-49- 33.77916

100660 38-23- 47.51830 119-49- 33.95818

100700 38-24- .60973 119-49- 34.13721

\|\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\--\|
\|\-\-\-\-\-\-\-\-\-\-\-\-\--\|

1 2 3

1 - Point ID

2 - NAD 27 Latitude

3 - NAD 27 Longitude

Description:

Latitude and Longitude in NAD 27 of the points.

GMM T06SR20E.LX

Geographic Coordinate Line File. For most Users.

T06NR20E MDM CA

ORIGIN 382203.0000 1194647.0000 257142.504250042.92

100100 381903.1716 1194947.4695 7000.00 69 83 1 1 2 252591.89 4244632.03

100120 381916.1290 1194947.3009 7000.00 72 237 1 1 3 252608.23
4245031.38

100140 381929.0864 1194947.1323 7000.00 72 237 1 1 3 252624.57
4245430.73

100160 381942.0438 1194946.9637 7000.00 72 237 1 1 3 252640.91
4245830.08

100200 381955.0011 1194946.7951 7000.00 72 237 1 1 3 252657.25
4246229.43

100220 382007.3819 1194946.0211 7000.00 75 237 1 1 3 252687.75
4246610.55

100240 382019.7626 1194945.2471 7000.00 75 237 1 1 3 252718.25
4246991.67

100260 382032.1434 1194944.4731 7000.00 75 237 1 1 3 252748.74
4247372.79

100300 382044.5241 1194943.6991 7000.00 75 109 1 1 3 252779.24
4247753.91

100320 382056.5435 1194942.7731 7000.00 882 378 1 1 3 252813.08
4248123.78

100340 382108.5628 1194941.8470 7000.00 450 1789 1 1 3 252846.92
4248493.64

100363 382120.5821 1194940.9209 7000.00 436 1790 1 1 4 252880.77
4248863.51

100383 382132.6014 1194939.9947 7000.00 727 324 2 1 2 252914.61
4249233.37

100400 382141.6810 1194939.4853 7000.00 224 148 2 1 3 252935.56
4249512.92

100403 382144.9159 1194939.4157 7000.00 224 163 2 1 4 252940.31
4249612.60

100463 382224.8856 1194935.8847 7000.00 225 153 3 1 2 253063.79
4250842.24

100500 382228.5644 1194935.7927 7000.00 225 131 3 1 3 253069.50
4250955.59

100513 382236.6109 1194935.3525 7000.00 687 278 3 1 4 253087.78
4251203.33

100540 382247.1214 1194934.5879 7000.00 932 353 4 1 2 253116.27
4251526.80

100560 382257.6319 1194933.8232 7000.00 846 318 4 1 3 253144.76
4251850.27

100600 382308.1423 1194933.0585 7000.00 95 83 4 1 3 253173.25 4252173.74

100620 382321.2846 1194933.4188 7000.00 96 339 4 1 3 253176.93
4252579.19

100640 382334.4268 1194933.7792 7000.00 96 339 4 1 3 253180.60
4252984.63

100660 382347.5183 1194933.9582 7000.00 96 271 4 1 3 253188.64
4253388.38

100700 382400.6097 1194934.1372 7000.00 96 72 4 1 4 253196.67 4253792.12

\|\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|
\|\-\-\-\--\| \|\-\-\-\--\| \| \| \|
\|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|

1 2 3 4 5 6 7 8

1 - Point ID

2 - NAD 27 Latitude/Longitude. The decimal is located after the seconds.

3 - Project elevation in feet.

4 - Error error ellipse axis rounded to the nearest foot.

5 - Line number code - see Index diagram on page 13.

6 - Line type code - 0 = solid (continuous), 2 = dashed, 3 = centerline

7 - Line draw code - 1 = skip, 2 = pen down, 3 = draw, 4 = pen up

8 - Universal Transverse Mercator (UTM) coordinates in meters. Cartesian
format - x,y.

Description:

This is a graphics line file. It can be imported into a GIS. Usually
used to produce graphic displays of the data

xxx.LX (GMM) FILE INDEX DIAGRAM

This is the sequence of line information as it shows up in the Lxx file.
It goes from South to North and then West to East.

![](media/image6.wmf)

GMM T06SR20E.PGC

Geographic Coordinate File. Only useful to GCDB.

T06NR20E MDM CA

ORIGIN 382203.0000 1194647.0000 7000.000 0 0 2000.0000 5000.0000

100100 381903.1716 1194947.4695 7000.000 69 83

100200 381955.0011 1194946.7951 7000.000 72 237

100300 382044.5241 1194943.6991 7000.000 75 109

100320 382056.5435 1194942.7731 7000.000 882 378

100340 382108.5628 1194941.8470 7000.000 450 1789

100363 382120.5821 1194940.9209 7000.000 436 1790

100383 382132.6014 1194939.9947 7000.000 727 324

100400 382141.6810 1194939.4853 7000.000 224 148

100403 382144.9159 1194939.4157 7000.000 224 163

100423 382158.2392 1194938.2388 7000.000 224 273

100443 382211.5624 1194937.0618 7000.000 224 272

100463 382224.8856 1194935.8847 7000.000 225 153

100500 382228.5644 1194935.7927 7000.000 225 131

100513 382236.6109 1194935.3525 7000.000 687 278

100540 382247.1214 1194934.5879 7000.000 932 353

100560 382257.6319 1194933.8232 7000.000 846 318

100600 382308.1423 1194933.0585 7000.000 95 83

100640 382334.4268 1194933.7792 7000.000 96 339

100660 382347.5183 1194933.9582 7000.000 96 271

100700 382400.6097 1194934.1372 7000.000 96 72

\|\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|
\|\-\-\-\-\--\| \|\-\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|

1 2 3 4 5

1 - Point ID

2 - NAD 27 Latitude/Longitude. The decimal is located after the seconds.

3 - Project elevation in feet.

4 - Error error ellipse axis rounded to the nearest foot.

5 - (X,Y) Cartesian tangent plane coordinates in chains unit. Origin is
assigned a false departure of 2000 chs. and latitude of 5000 chs.

Description:

This is a geographic coordinate file used by GMM programs.

GMM T06SR20E.RAW

Raw Data File. Only useful to GCDB.

T06SR20E MDM CA

999999

100100 100200 80.000 1 .0 1879WB

100200 100300 80.000 1 .0 1879WB

100300 100320 20.000 1 .0 A1879WB

100320 100340 20.000 1 .0 A1879WB

100340 100363 20.000 1 .0 A1879WB

100363 100383 20.000 1 .0 A1879WB

100383 100400 15.059 1 .0 A1879WB

100400 100403 4.941 1 .0 1879WB

*and a little further down\...*

700100 657100 19.300 3 900000.0 1874SB

657100 637100 20.150 3 900000.0 1874SB

637100 617100 20.150 3 900000.0 1874SB

617100 600100 20.400 3 900000.0 1874SB

600100 577100 .091 3 900000.0 1874SB

577100 557100 20.492 3 900000.0 1874SB

557100 540100 19.417 3 900000.0 1874SB

540100 537100 1.075 3 890725.0 26RS084

*and a little further down\.....*

240700 200700 40.000 3 900000.0 PROT122

200700 100700 80.000 3 900000.0 PROT122

400240 300240 79.000 4 874200.0 1981

200640 240640 40.000 1 900000.0 1879

240640 240700 40.000 1 .0 1879

999998

\|\-\-\-\-\-\-\-\-\-\-\-\--\| \|\-\-\--\| \| \|\-\-\-\-\--\|
\|\-\-\-\-\--\|

1 2 3 4 5

1 - From and to Point IDs.

2 - Distance, in chains, between the points.

3 - Bearing quadrant ( 1=NE, 2=SE, 3=SW, 4=NW)

4 - Bearing in degrees, minutes, and seconds. The decimal point is
located after the seconds.

5 - Source Identifier number (SID). Each data source, whether it is an
official cadastral survey plat, state or local survey plat, deeds, etc.,
utilized in generating coordinates for the GCDB, will be assigned a
unique SID number. A SID with a letter prefix has augmented error
estimates. A SID with a letter suffix denotes that there is more than
one survey for the same year. A SID with boundary designations will have
a NB, EB, SB or WB for a suffix.

Description:

This is the raw data on which GMM performs it computations. It is
abstracted from the survey records and entered into GMM.

GMM T06SR20E.SID

Information File. Only useful to GCDB.

S26RS084 .100 100.0 11.0 40.000 40.000

C CA109 1982 D

S1981 .100 100.0 11.0 40.000 40.000

C BLM 13-DEC-1982 D JEPSON, WOODROW L.

S1928 .100 333.3 31.0 40.000 40.000

C GLO 02-MAR-1932 D AVERILL, DUPREE R.

S1879 .100 18000.0 4500.0 40.000 40.000

C GLO 21-JAN-1880 O ANDERSON, J.M.

S1874SB .100 1000.0 300.0 40.000 40.000

C GLO 21-JAN-1880 O BENSON & GLOVER

SPROT122 .100 100.0 6300.0 40.000 40.000

C BLM 27-JAN-1970 P

S1879WB .100 1562.5 18000.0 40.000 40.000

C GLO 21-JAN-1880 O ANDERSON, J.M.

S1879NB .100 3125.0 3000.0 40.000 40.000

C GLO 21-JAN-1880 O ANDERSON, J.M.

SA1879WB .100300000.0 28200.0 40.000 40.000

C GLO 21-JAN-1880 O ANDERSON, J.M.

SA1879 .100 1562.5 12000.0 40.000 40.000

C GLO 21-JAN-1880 O ANDERSON, J.M.

S1879 - SID code (Year the survey was conducted if BLM/GLO)

0.100 - Constant error estimate.

100.0 - Distance error estimate in PPM (parts per million).

11.0 - Error estimate in seconds.

40.000 - These 2 fields are not used. The numbers are irrelevant.

C - Comment line.

GLO - Agency source code, See Table A on page 20.

10-OCT-1916 - Date of approval of the SURVEY, put in by data abstractor.

O - Code for type of survey. See Table B on page 20.

Bardsley,HG - Name of Surveyor.

Description:

This file contains information about the surveys used for this township.
It shows the SID number, survey source, date of survey, surveyor and
some reliability values.

GMM T06SR20E.UTM

Geographic Coordinate File. Useful to UTM users.

TWP 03S RNG 39E PM Boise Idaho(ID) DATE 92/12/03

ORIGIN 430900.0000 1115300.0000 6107.00 0 0 428174.124777635.76

700100 430627.6337 1114932.5922 6107.00 22 22 432812.504772887.89

700117 430638.0782 1114932.5901 6107.00 22 21 432815.734773210.07

700120 430640.6688 1114932.5900 6107.00 22 21 432816.514773289.98

700137 430651.1165 1114932.5878 6107.00 21 21 432819.744773612.26

700140 430653.7038 1114932.5877 6107.00 21 21 432820.534773692.08

700157 430704.1548 1114932.5856 6107.00 21 21 432823.754774014.46

700160 430706.7389 1114932.5854 6107.00 21 21 432824.544774094.17

700197 430717.1931 1114932.5833 6107.00 20 20 432827.764774416.65

700200 430719.7739 1114932.5831 6107.00 20 20 432828.554774496.27

*and further down in the file\.....*

100640 431114.6980 1115634.3899 6107.00 0 0 423378.514781843.65

100660 431127.7231 1115634.3490 6107.00 0 0 423383.964782245.44

100700 431144.1412 1115634.2974 6107.00 0 0 423390.834782751.89

640100 430627.6855 1115008.1917 6107.00 23 23 432007.884772897.46

540100 430627.7967 1115119.3741 6107.00 23 23 430399.024772917.11

440100 430627.9004 1115230.5835 6107.00 22 22 428789.554772936.92

340100 430627.9789 1115341.8584 6107.00 20 20 427178.594772956.35

240100 430628.0397 1115453.1879 6107.00 18 18 425566.394772975.63

140100 430628.1010 1115604.5570 6107.00 7 7 423953.304772995.31

120100 430628.1248 1115622.3762 6107.00 4 5 423550.554773000.55

\|\-\-\--\| \|\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--\|
\|\-\-\-\--\| \|\-\-\-\--\| \|\-\-\-\-\-\--\|\|\-\-\-\-\-\-\--\|

1 2 3 4 5 6

1 - Point ID

2 - NAD 27 Latitude/Longitude. The decimal is located after the seconds.

3 - Project elevation in feet.

4 - Error error ellipse axis rounded to the nearest foot.

5 - Universal Transverse Mercator (UTM) coordinates in meters, x value.

6 - UTMs in meters, y value.

Description:

This file contains UTM coordinates for all the points in the township.

**APPENDIX A - GMM Glossary**

**Observation** - a fancy word for measurement

**Simultaneous Solution** - this means all coordinates are being solved
for in one solution; In the compass rule process you must adjust one
traverse into another traverse which is held as \"fixed\". This is not
correct since the fixed traverse contains error.

**System of Equations** - in a least squares adjustment you solve an \"n
x n\" system of equations each iteration where n equals the number of
unknown quantities. In a 20 station traverse there are 40 unknowns (20
N, 20 E coordinates). This means a 40 equations, 40 unknowns system of
equations must be solved. Even for a computer this is a slow process.

**Bandwidth Optimization** - There are many ways to speed up the
solution of a system of equations and reduce the number of terms in the
equations. Some methods other than bandwidth optimization include column
profile minimization, Helmert blocking, and recursive partitioning. If a
computer program does not use one of these methods the results will be
produced very slowly. LSAQ uses a bandwidth optimization routine which
has been extensively modified for better performance. For most survey
networks the bandwidth will probably range from 5-30% of the total
number of stations. This process enables more efficient solution of
least squares problems, and especially allows \"big\" problems to be
solved on a personal computer

**Solution Convergence** - the last iteration has insignificant updates
and thus the solution terminates.

**Solution Divergence** - blunders or poor initial approximations will
cause updates to grow as iterations proceed; This indicates something is
wrong with the data, and it needs to be corrected.

**Number of measurements** - equals \# of distances + number of angles +
number of azimuths + number of control coordinates

**Degrees of freedom** - number of measurements minus number of
unknowns; or the number of measurements beyond what is necessary to
uniquely define coordinates for each station

**Residual** - the difference between a measurement and its computed
quantity based on coordinates; It is how much the measurement adjusted.

**Error estimate** - A surveyor\'s error estimates of measurements
assigns appropriate weighting of measurements in a least squares
adjustment. An angle with an error estimate of 2 seconds will be treated
as more weighted (stronger, less chance of adjustment) than an angle
with an error estimate of 10 seconds. This does not mean the angle with
the smaller error estimate will always get a smaller adjustment since
geometric constraints ( such as sum of angles in a closed figure) also
play a major role in dictating amount of adjustment. A distance error
estimate is usually modeled by a constant plus a ppm addition to account
for larger errors generally occurring in longer lines. An angle or
azimuth error estimate is a function of the instrument\'s least count,
the number of repetitions, the instrument operator\'s abilities, and the
prevailing environmental conditions. Experience with instrumentation and
the least squares adjustment will allow the surveyor to develop
confidence in error estimation. Error estimating allows the simultaneous
analysis of different measurement types (distances, angles, azimuths,
control coordinates).

**RMS error** - root mean square error - it is the average of a series
of residuals in which the sign of the residual is eliminated through
summing squared residuals, dividing by the number of that type of
measurement, then computed that value\'s square root.

**Residual vs. error estimate** - These quantities should be of
approximately the same magnitude. Since measurements contain random
error a plot of residuals should look like the \"bell-shaped\" curve
from statistics which centers about zero. If residuals tend to be
predominantly of one sign this means systematic error may exist. This
would occur if your survey tied into two precise control coordinates and
your EDM was measuring systematically long. All adjusted distances would
be shorter than their measured values. It could also occur if horizontal
angles were only measured in the direct position and a large horizontal
collimation error existed. Residuals which are larger than three times
their respective error estimate are generally considered suspect.

**Standard error of unit weight** - This is a number which tells you how
well it appears you that you are estimating your measurement errors. It
is generated by the summing the squares of all residuals divided by
their error estimates. That quantity is divided by the degrees of
freedom and the square root is taken. If a residual and error estimate
are of the same magnitude note that the residual divided by the error
estimate will generally produce a number close to one. The standard
error of unit weight is a number that evaluates all residuals and
corresponding error estimates. If the standard error of unit weight is
near one (0.7-2.5) you are estimating your errors well. Uncorrected
systematic errors, blunders, or generally poor measurements will result
in larger residuals and thus a large standard error of unit weight. If
you are pessimistic in error estimation or you have very few redundant
measurements a very small standard error of unit weight will result.

**Standard error of adjusted coordinates** - these are the least squares
error estimates of adjusting N,E coordinates. They are a function of
proximity to existing control points. The statistical significance of
these quantities is that if you went and made the same measurements with
the same instrument using the same procedures, you would have a one
sigma (68.3% confidence) chance of being within plus or minus the
standard error of the first solution\'s coordinate. It has nothing to do
with additional traverse legs and readjustment, comparing to someone
else\'s coordinates, or evaluating retracement evidence.

**Error ellipses** - It should be apparent that the reliability of a
traverse point\'s position will not usually be the same in all
directions. The position is generally stronger in the traverse
direction, and weakest away from the traverse directions. The error
region is an ellipse, defined by a radius (semi-major axis) of maximum
error (SU), radius (semi-minor axis) of minimum error (SV), and the
angle from north (positive clockwise) of the direction of maximum error
(T). Since an error ellipse is two-dimensional, the one sigma error
ellipse only denotes 35% confidence (roughly 68.3% squared). The same
statistical significance reasoning for coordinate standard errors
applies to error ellipses - it is an internal evaluation of your data
and does not relate to external information such as other surveys or
existing coordinates.

**Robustness** - This is a method of using least squares as a filtering
mechanism for detection of blunders. Robustness averages the absolute
value of a measurement\'s residual with its error estimate, and that
average becomes the new error estimate in a readjustment. The
measurements with large residuals get reassigned larger error estimates,
and vice-versa. This enables the adjustment to be filtered to the
suspect measurement. The success of robustness in blunder detection is a
function of size of the blunder, number of blunders, and the geometry
and redundancy of the traverse network.

**NAD 27** - North American Datum of 1927 - a datum based on the Clarke
Ellipsoid of 1866, and fixed position and orientation at Meade\'s Ranch
in Kansas. Based upon this information latitudes and longitudes were
calculated for all National Geodetic Survey control points based
primarily on triangulation. The calculation involved a least squares
adjustment by hand calculations!

**NAD 83** - North American Datum of 1983 - a datum based on the GRS 80
Ellipsoid, and fixed position and orientation at the center of the
earth. The measurements used in NAD 27, and additional measurements made
by the National Geodetic Survey subsequent to 1927, were subjected to a
least squares adjustment - this time using a computer. This results in a
different latitude and longitude for a station when compared to its NAD
27 values, with the difference often amounting to hundreds of feet.

**State Plane Coordinates** - projections which uniquely relates a
geodetic position (latitude, longitude) to a plane coordinate pair
(N,E). The relation is truly a one-to-one correspondence; for a unique
state plane coordinate pair there is only one latitude, longitude pair,
and vice-versa. The two type of projections that exist are Lambert - a
conic projection for states elongated east-west, and Mercator - a
cylindrical projection for states elongated north-south. The size of a
zone was limited by defining a a state plane distance will not differ
from its geodetic counterpart by 1/10000 of the distance. Thus larger
states are covered by more than zone.

**NAD 27 state plane coordinates** - These are based on zone constants
which include false northings and eastings so that negative coordinates
do not result. The published units are U.S. Survey Feet.

**NAD 83 state plane coordinates** - These are based on different zone
constants than NAD 27. The most notable change is that different values
were assigned for false northings and eastings, and the coordinates
published by NGS are in meters instead of U.S. Survey Feet. Even when
converted to feet, NAD 83 coordinates look dramatically different than
the NAD 27 coordinates for the same point because the false northings
and eastings are different.

[^1]: ^?^Townships with 26 or more Special Surveys may not have Special
    Surveys included, but will have the PLSS rectangular surveys
    included.

[^2]: *Chains are a unit of measure used by surveyors. A regular section
    is 80 chains square. One chain equals 66 feet. One hundred links
    equal one chain.*