help TIGERARC

TIGERARC <in_tiger_file_prefix> {out_cover} {out_point_cover}
        {out_landmark_cover}
 
converts a set of U.S. Bureau of Census TIGER/Line files into one or
more ARC/INFO coverages.
 
arguments <in_tiger_file_prefix> - the file name prefix for files to be
converted.  File names must include the prefix concatenated with the
record type identifier.  The file prefix may include a directory
pathname and extension.
 
{out_cover} - the name of the output coverage to be created
containing all the basic line features and attribute data from the set
of TIGER/Line files.
 
{out_point_cover} - the name of the output coverage that contains
point features that represent polygon label points for polygons in
{out_cover}.
 
{out_landmark_cover} - the name of the output point coverage
containing landmark features.

notes
At least one output coverage must be specified.
 
TIGER/Line files are an extract of selected information from a digital
database maintained internally by the U.S. Census Bureau.  This
extract is available in ASCII format on both CD-ROM (compact disk
read-only memory) and tape medias.
 
TIGERARC converts all versions released after April 1989.  A
prototype version was released prior to this date and has a slightly
different file structure than later versions.  The TIGERPROTO
command can be used to convert files in this earlier prototype
format.
 
The same permanent record numbers for line segments in the TIGER
database will be maintained by the U.S. Census Bureau throughout all
versions.  A permanent record number will be deleted only if the
line segment itself changes physically.  The U.S. Census Bureau then
assigns a new number for that segment, and the original number is
retired.
 
TIGER/Line files are partitioned into counties ranging in size from
less than a megabyte to almost 120 megabytes, the average size is
around 10 megabytes.
 
To determine the amount of disk space required to convert a set of
TIGER/Line files, use this rule of thumb:  the size of the converted
coverage(s) is approximately the same size as the files used in the
conversion.  The amount of additional scratch space needed depends
on the largest file and whether or not it will need to be sorted.  The
amount usually required is about double the size of the file being
sorted.
 
The number of files in a TIGER/Line file set provided by the Census
Bureau depends on the version.  The number of files increases with
each new release.  Each new extract from the TIGER system includes
an updated version of the same files from the previous release, plus
additional files containing additional information from the TIGER
database.
 
The precensus version is the earliest supported by the TIGERARC
command and contains files type 1 thru 6.  These files contain the
basic line feature and attribute data.
 
The Initial Voting District is an intermediate version released prior to
the final 1990 census and contains the same six files provided by the
precensus version plus four additional files type 7, 8, I and P.  These
files contain landmark feature and polygon location information.
 
The final 1990 census version includes files from the previous Initial
Voting District version plus file type A containing polygon attributes
and file type R containing general information.  File type R is an
ASCII file that contains information about the range of data in the
file set and is not converted by the TIGERARC command.
 
The Census Bureau provides the final 1990 Census version of
TIGER/Line files on CD-ROM in a format that can be read directly by
the TIGERARC command.  The directory structure is a state directory
and a number of county subdirectories.  Each county subdirectory
contains a complete set of TIGER/Line files for that county.  A state
may extend over several CDs, but counties fit entirely on one CD.
 
The files converted by TIGERARC will depend on the options
specified and the version of TIGER/Line files being used.  Use the
table provided to determine the files each option uses in the
conversion.
 
Only those files in the workspace directory specified by
<in_tiger_file_prefix> will be used in the conversion.  If the file prefix
does not include a pathname, files in the current workspace directory
will be used.  Files that are not required for the options specified and
are not needed for your particular application can be renamed or
deleted.  Files on CD-ROM will have to be copied to disk first before
they can be renamed or deleted.
 
The output coverages for TIGERARC will always be in double
precesion regardless of the current creation rule established by the
PRECISION command.  TIGER/Line files often contain tiny line
segments that would lost if converted to single precision.
 
Refer to the chapter on 'Converting street network data' in the Data
Conversion User's Guide for further information about TIGER files
and processing steps.
 
Files type 1 thru 6 are available for all versions of TIGER/Line files.
 
 
Converting line features
The {out_cover} option is used to convert basic TIGER/Line feature
and attribute data from files type 1 thru 6.  The out_cover will
contain line features, TIC and BND files and an INFO file named
out_cover.ACODE.  An additional INFO file, out_cover.TYPE3, may also
be created to store attributes from file type 3.
 
Type 1 - an ASCII file storing type 1 TIGER/Line records, also known
as the basic data record file.
 
File type 1 contains the basic data for each line segment.  The
latitude and longitude for the beginning and ending points of each
line segment are provided as well as a set of feature attributes.
Attribute information includes a permanent record number, file
history, feature type, street address, and both legal and statistical
area boundaries.  The shape points for each line segment are in file
type 2.  Both files are required for this option.
 
File history attributes - include record type, version number and the
source data for each line segment.
 
Feature type - includes census feature class codes for roads,
transportation, hydrography and other physical features.
 
Street address information - includes standard geocoding items:
street name and type, address range, prefix and suffix directions and
ZIP codes.
 
Legal area boundaries - the left and right area boundaries for each
line segment.  Legal areas include state, county, minor civil divisions,
Indian reservations and other native regional areas.
 
Statistical area boundaries - left and right areas defined and used
during the census taken including census blocks, block groups, tracts,
designated places and other statistically equivalent areas.
 
An INFO data file named out_cover.ACODE is created to store the
attributes for line features converted from file type 1.  The ACODE
file is linked to line features in {out_cover} by User-ID.  The User-ID
stores the permanent record number for each line feature.  There
will be one record in the ACODE file for every line segment in file
type 1.
 
Type 2 - an ASCII file storing type 2 TIGER/Line records, also known
as the shape coordinate points file.
 
This file provides the shape points for line segments in file type 1.
All coordinates are expressed in degrees and decimal fractions of a
degree of latitude and longitude.  The decimals are carried to six
places.  If a line segment is straight, there will be no shape
coordinate points.  Line segments that have more than 500 shape
points will be split into two arcs with the same User-ID.  Both files
type 1 and 2 are required for the in_cover option.
 
Type 3 - an ASCII file storing type 3 TIGER/Line records, also known
as the 1980 Census geographic codes.
 
This file provides 1980 census codes for the left and right sides of
each line segment in file type 1.  Also included are 1990 geographic
area codes and voting district codes not in file type 1.  This file is
optional.
 
If file type 3 is converted, an additional INFO data file named
out_cover.TYPE3 is created to store decennial information for each
line feature.  There is one record in out_cover.TYPE3 for every line
segment in file type 1.
 
Type 4 - an ASCII file storing type 4 TIGER/Line records, also known
as the Index to alternate feature names file.
 
This file is not directly converted but provides an index to a list of
alternate feature names in file type 5.  This file is optional but cannot
be used independently of file type 5.
 
Type 5 - an ASCII file storing type 5 TIGER/Line records, also known
as the feature name list file.
 
If files type 4 and 5 are used, attributes for line segments in file type
1 with alternate street names will have following items updated:
 
RT      Record Type
FDPRE   Feature Direction, Prefix
FNAME   Feature Name
FTYPE   Feature Type
FDSUF   Feature Direction, Suffix
 
The remaining attribute information for the line segment is
duplicated including the User-ID.  The duplicate records are written
to the ACODE file.  These added records give the ACODE file a many-
to-one relationship to the arcs, and the ACODE file is no longer
ordered on User-ID.  You can use the INFO SORT command on the
User-ID in the ACODE file to enhance performance of certain
procedures such as the ARC RELATE command.  This file is optional
but cannot be used independently of file type 4.
 
Type 6 - an ASCII file storing type 6 TIGER/Line records, also known
as the additional address & ZIP code data file.
 
This file provides additional address range and ZIP code information
for line segments in file type 1 that cannot be represented by a
single address range.  The following address range and ZIP code
items are updated:
 
RT              Record Type
LEFTADD1        Left From Address
LEFTADD2        Left To Address
RGTADD1         Right From Address
RGTADD2         Right To Address
ZIPCOLEF        Left ZIP code
ZIPCORGT        Right ZIP code
 
If file type 6 is used, the address range and ZIP code information are
updated and the rest of the attribute information, including the
User-ID, is duplicated.  The duplicate records are appended to the
ACODE file after the data from type 1 and any type 5 records.  This
file is optional.
 
 
Using {point_cover}
The {out_point_cover} option is used to convert polygon locations and
area attributes from files type P, I and A.  The output cover will have
points, TIC and BND files and an INFO data file named
{out_point_cover}.XCODE.  Two additional INFO data files named
point_cover.TYPEI and point_cover.TYPEA may be created to store
information from files type I and A.
 
The point features represent polygon label points for polygons in
{out_cover}.  There is one polygon location provided for every
polygon defined by the Census Bureau.  There may not be one
polygon location for every polygon in the converted {out_cover}.
 
Some point features may not fall within the polygons they are
intended to represent.  Any corrections should be made prior to
overlaying points in {out_point_cover} with the lines in the
{out_cover}.
 
Type P - an ASCII file storing type P TIGER/Line records, also known
as the Polygon Locations file.
 
This file provides polygon locations that are used to generate point
features in {out_point_cover}.  These point features represent
polygon lables for {out_cover}.
 
An INFO data file named point_cover.XCODE is created from file type
P.  Each record in the XCODE file contains a polygon identifier and file
history attributes.  Type P is only available for versions later than
precensus.  This file is required for the {out_point_cover} option.
 
Type I - an ASCII file storing type I TIGER/Line records, also known
as the Area Boundaries file.
 
This file provides the links to the area boundaries stored as left and
right attributes for line features in {out_cover}.  Type I is only
available for versions later than precensus.  This file is optional.
 
If type I is used, an INFO data file named point_cover.TYPEI will be
created.  There is one record in point_cover.TYPEI for every line
segment in file type 1.  Each record in TYPEI will contain the
permanent record number for the line feature and the left and right
polygon identifiers.  This file is optional.
 
Type A - an ASCII file storing type A TIGER/Line records, also
known as the Additional Polygon Geographic Area Codes file.
 
This file is only available for the final 1990 census version and later.
This is a key file in that it provides the area attributes for polygons
that in previous versions were stored only as left and right area
boundaries for line segments.
 
If file type A is used, an INFO data file named point_cover.TYPEA
will be created containing a set of area attributes and polygon
identifiers that can be linked to points representing polygons in
{out_point_cover}.  There is one record in TYPEA for every polygon
location in file type P.  This file is optional.
 
Converting landmarks
There are two types of landmark features stored in the TIGER/Line
files:  landmark points and landmark area attributes.  The
{out_landmark_cover} option converts file type 7 to landmark point
features and attributes, and file type 8 to area attributes with a
polygon identifier that can be linked to point features representing
polygons in {out_point_cover}.  Files type 7 and 8 are available for
the Initial Voting District version and later.
 
Type 7 - an ASCII file storing type 7 TIGER/Line records, also known
as the Landmark Features file.  This file provides the location for
landmark point features and a set of attributes including file history,
and landmark feature name.
 
File type 7 stores points in {out_landmark_cover} and attributes in
an INFO data file named landmark_cover.XCODE.  There will be one
record in XCODE for every landmark point feature
{out_landmark_cover}.
 
File type 7 also provides attributes and an index to area landmarks
in file type 8.  Both files type 7 and 8 are required for this option.
 
Type 8 - an ASCII file storing type 8 TIGER/Line records, also known
as the Area Landmarks file.
 
File type 8 converts to an INFO data file named
landmark_cover.TYPE8 containing a set of area attributes for area
landmark features and a polygon identifier that can be linked to
points representing polygon labels in {out_point_cover}.
 
Files type 3, 4, 5, 6 and A are used but not required by any of the
options and can be renamed or deleted if you do not want to include
them in the conversion.  Files on CD-ROM will have to be copied to
disk before they can be renamed or deleted.
 