Technical Documentation



                                
                                             
                                          
                                          
                                       

                   a public-domain data extraction utility
                  designed to work with Census Bureau files
                             in dBase III+ format
                                                                (release 1.5f)

To purchase CD-ROMs with Census           The EXTRACT program is distributed
Bureau statistics usable with             on Economic Census and other CD-ROMs.
this program, contact--                   
                                          Software and auxiliary file
     Customer Services                    updates are available through the
     Bureau of the Census                 Census Bureau electronic
     Washington, D.C.  20233              bulletin board:   301/457-2310
     301/763-INFO(4636)                         voice:            301/457-1242




                               TABLE OF CONTENTS 
 
Description of the Program . . . . . 1    Advanced Topics. . . . . . . . . .  24
                                             Auxiliary files and functions .  24
Getting Started. . . . . . . . . . . 1       Setting up an EXTRACT menu. . .  25
                                             File manipulation . . . . . . .  26
Stepping Through the Program . . . . 4       How to select records with 
   Specify drives on your machine. . 4         conditional clauses . . . . .  32
   Choose a catalog. . . . . . . . . 5       Displaying secondary files. . .  33
   Main help screen. . . . . . . . . 6       How to get EXTRACT to work with
   Select a database . . . . . . . . 6         other dBase files . . . . . .  33
   Main menu . . . . . . . . . . . . 7
      1)  Select Items . . . . . . . 8    Notes on Use of EXTRACT with--
      2)  Select Records . . . . .  10       1987 Economic Censuses. . . . .  35
      3)  Add Labels . . . . . . .  15       1987 Census of Agriculture. . .  36
      4)  Manipulate Files . . . .  16       U.S. Exports and Imports. . . .  38
      5)  Format Options . . . . .  17       County Business Patterns. . . .  38
      6)  Display to Screen. . . .  18       County and City Data Book, 1988  39
      7)  Print. . . . . . . . . .  21       USA Counties, 1992. . . . . . .  39
      8)  Extract Data to a File .  21       1990 Census: STF 1A, 3A, etc. .  39
      9)  Return to File Selection 
            Menu . . . . . . . . .  23    Getting Assistance . . . . . . . .  43
     10)  Advanced Options . . . .  23    INDEX . . . . . . . . . . . . . .   44

November, 1992  (minor revisions March 1993 and January 1995)



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DESCRIPTION OF THE PROGRAM

EXTRACT selects, displays and extracts data from dBase III+ files without using
dBase III+TM.  While the program is primarily designed to operate on files
issued from the Census Bureau's economic and agriculture censuses on CD-ROM, it
can work with any dBase III+ for which appropriate "catalog" and "data diction-
ary" files have been constructed (see Advanced Topics, below).

EXTRACT prompts the user through the selection of a file, the selection of data
items and records, the addition of text labels to displays and printouts, and
the extraction of data to a new file.  File output may be saved to a hard disk
or floppy in any of three formats so that data may be imported into other
programs, such as spreadsheets, statistical packages, graphics software and a
wide variety of other packages.

While many packages, like Lotus 1-2-3TM, can convert dBase III+ files using
their own utilities, they may not be able to deal with files as large as those
distributed by the Census Bureau, nor may they be able to incorporate descrip-
tive information from external data dictionaries.  EXTRACT pulls all of these
elements together for the user.  Help screens can provide definitions of
concepts.  The program includes limited computational capabilities, although
users planning to load EXTRACT output into a spreadsheet or statistical package
may prefer to defer computations to the applications software.

A general note on program speed:  Most of the files this program has been
designed to work on are very large, and CD-ROM readers are relatively slow
devices, much slower than hard disks.  Patience is called for when working with
large files.

+------------------------------------------------------------------------------+
| Tutorials are available.  This document is structured as a reference manual, |
| systematically describing each feature of the program.  If you would prefer  |
| to learn the software through a series of exercises with particular CD-ROMs, |
| read the EXTUTOR text files distributed with the EXTRACT program.  EXTUTOR1  |
| and EXTUTOR2 illustrate economic census files; EXTUTOR4 works through the    |
| use of 1990 census CD-ROMs, focussing on STF 1A; EXTUTOR5 deals with EEO CDs.|
+------------------------------------------------------------------------------+


GETTING STARTED

Hardware and Software Requirements

EXTRACT works best on a computer equipped with a hard disk.  During data extrac-
tion, the system may need to create temporary files, and thus works best when
there is extra disk space available.

                                                  1

EXTRACT requires about 450 kb of system memory (RAM) under DOS 3.x, up to 520 kb
under DOS 5.  A 512- or 640-kb machine should be fine as long as memory-
resident programs and CD-ROM or network drivers do not substantially reduce
available memory.  (DOS 5.0 users should load DOS and CD-ROM drivers "high".)

If you are using Census Bureau CD-ROMs issued in 1989 or later, your system must
also have MicroSoft Extensions 2.0 or later.  One way to check is to look for
the file MSCDEX.EXE on your computer and make sure it has a date of 1988 or
later.  

Installing Files on a Hard Disk

To install EXTRACT from a diskette onto a hard disk, copy the EXTRACT program
and related files to any desired directory on your hard disk, and create a
separate subdirectory for work space.  For example, at the C> prompt, type
     MD \EXTRACT
     CD \EXTRACT
     MD WORK

Insert the EXTRACT program diskette in the A: drive and type
     A:EXT15x      (x varies with the current version)

EXT15x is a program that creates uncompressed copies of EXTRACT.EXE (version
1.5x), related files, and EXTRACT.DOC, an ASCII text version of this documenta-
tion, and stores them on your current (default) drive and directory.

If you obtained this program on a CD-ROM, the program INSTALL.BAT will copy
EXTRACT and related files to the drive and directory you specify.  The syntax is
     [CD]:\EXTRACT\INSTALL [CD]: [DRIVE]:\[DIRECTORY]

where [CD] is the drive letter for your CD-ROM and [DRIVE]:\[DIRECTORY] is the
drive letter and directory on your hard disk where you want EXTRACT and related
files to reside.

Steps for all users.  Check whether you have a "CONFIG.SYS" file in the root
directory (type DIR C:\CONFIG.SYS).  If you do not, create one at the C> prompt
by typing
     COPY CON CONFIG.SYS
     FILES = 20
     BUFFERS = 20
then press the <F6> key followed by <ENTER>.

If you already have a config.sys file, make sure that it contains lines which
say FILES = 20 and BUFFERS = 20 (or higher number), or change it with a text
editor.

If you are using a CD-ROM that does not contain EXTRACT-compatible auxiliary
files (e.g., 1988 County and City Data Book, Imports, Exports, 1990 census
discs) you must install files from a separate Auxiliary Files diskette.  Put the
disk it in the A: drive, display a directory (DIR A:) and type out any file with
a title including "READ.ME", for example "FTD_READ.ME".  That file will contain
instructions on loading the files into appropriate directories on your hard
disk.

EXTRACT requires about 450 kilobytes of random access memory (RAM) under DOS
3.x, or up to 520 kb under DOS 5.  If the program aborts with a "run error",

                                                  2
you do not have enough memory available to complete the requested task.  To
determine the amount of RAM available, run the DOS CHKDSK program, and examine
the last line of output.  If you have insufficient memory available, you may
need to remove terminate-and-stay-resident programs (TSRs) or network drivers
and reboot.  If you have more than 640 kilobytes of RAM and use a memory manager
such as QEMM(tm), you will need to enter the following command at the DOS prompt
before running EXTRACT.  (Saving parameters, as discussed below, automatically
adds this line to batch files.)

    SET CLIPPER=E000

If you do not have access to a CD-ROM, you may try out the program with test
data and auxiliary files contained in TESTDATA.EXE and TEST_AUX.EXE, available
separately.  When uncompressed, these files from the 1987 Census of Retail Trade
for Arizona require about 665 kb on your hard disk.  See instructions in the
corresponding TST_READ.ME file.

If you have had to create or change your config.sys file, you will need to
reboot before proceeding further.

Starting the Program

Make the directory with the EXTRACT files the default directory (e.g., by typing
CD \EXTRACT), then type
     EXTRACT
(If nothing happens, type EXTRCT14 to uncompress the files before proceeding.)

Once the program is running, using EXTRACT should be reasonably self-ex-
planatory, since most options are presented as items on a menu.  On-line help is
available at most points during the program by pressing the <F1> key.




























                                                  3
STEPPING THROUGH THE PROGRAM

Specify Drives on Your Machine

Since EXTRACT is designed to work in a variety of different environments, with
data residing on a floppy disk, hard disk, or CD-ROM, the program normally asks
first for the location of the files it requires.  If parameters have already
been saved (see below), this screen is skipped.

+------------------------------------------------------------------------------+
|                        SPECIFY DRIVES ON YOUR MACHINE                        |
|                                                                              |
|                                                                              |
| Enter DRIVE letter for CD-ROM (blank if none), then press <ENTER>            |
| :  l:                                                                        |
|                                                                              |
| Enter DRIVE and DIRECTORY for WORKSPACE on your hard disk                    |
|        e.g., 'C:\EXTRACT\WORK'                                               |
| :  c:\extract\work                                                           |
| Enter DRIVE and DIRECTORY for AUXILIARY FILES                                |
| :  c:\extract\cbpauxil                                                       |
|                                                                              |
|          Is this information correct?   y                                    |
|           <Y>es, <N>o, <S>ave, <Q>uit                                        |
|                                                                              |
|                                                                              |
|                                                                              |
|      Enter DRIVE and DIRECTORY information in the following format:          |
|            <drive>:\[<directory>]      -- then press <ENTER>                 |
+------------------------------------------------------------------------------+

If you are using a CD-ROM, specify the drive letter.  Many CD-ROMs are desig-
nated the L: drive; if so, simply type L: and press <enter>.  Next, the system
asks you to specify a drive and directory for work space, e.g. C:\EXTRACT\WORK. 
If the CD-ROM does not include catalog (*.CTG) and data dictionary (*.DCT) files
for the data, the system will ask for their location; for economic census,
agriculture census, and recent County Business Patterns discs, this third prompt
does not appear.

Since EXTRACT will not find the files it needs unless drives are correctly
specified, the system asks "Is this information correct?" before proceeding. 
Type "Y" or "y" for yes.  If the response is "N" or "n", the system will ask
each of the questions over again.  Entering "S" or "s" will <S>ave the drive and
directory information to a batch file.  Typing "Q" at this point will quit the
program.

Saving Parameters  When the <S>ave option is exercised, the system prompts you
to name a batch file, e.g., EXCBP for County Business Patterns.  Typing that
name (EXCBP) rather than EXTRACT in the future will skip this drive selection
screen.  You should have a separate name for each different setting you need. 
Typing EXMENU will list each option you have created.  (See also the discussion
of command-line parameters on page 23.)

Selecting a Master Catalog  EXTRACT relies on a "master catalog", usually named
MASTER.CTG, to direct file selection activities.  Some sets of auxiliary files
have more than one master catalog.  For example the 1990 census auxiliaries
include a MSTRST1A.CTG for STF 1A CD-ROMs, MSTRST1B.CTG for STF 1B, etc.  If

                                                  4
applicable, a small window will open in the lower left of the screen and you
will be prompted to select the appropriate master catalog file.

If you are using a CD-ROM, EXTRACT will check for the file MSCDEX.EXE in your
root directory.  If it finds an out-of-date version, or if it fails to find the
file at all, EXTRACT will display a message to that effect, but you may be able
to ignore the message if the program then works correctly, since the operative
MSCDEX.EXE may be in a subdirectory on your hard disk.

Choose a Catalog

Files are grouped into "catalogs" or groups of similar files.  Highlight the
appropriate one with the up or down arrow keys and select with <ENTER>.

+------------------------------------------------------------------------------+
|                        CHOOSE A CATALOG                                      |
|                                                                              |
|1. Position cursor by using <PgUp>, <PgDn>, < >, or < >                       |
|2. Press <ENTER> to select a catalog.                                         |
|                                                                              |
|CATALOG    DESCRIPTION                                                        |
|==============================================================================|
|RC87A1__ | 1987 RETAIL TRADE:  Detailed Stat's for State, Places,Counties,MSAs|
|RC87A2__ | 1987 Retail Trade:  State Bridge Tables (old/new SIC) + ratios     |
|RC87A3__ | 1987 Retail Trade:  Summary Statistics for State, Counties & Places|
|RC87A4__ | 1987 Retail Trade:  Rankings for Counties and Places               |
|RC87N1__ | 1987 Retail Trade:  Employers and Nonemployers--U.S. by SIC        |
|RC87N2__ | 1987 Retail Trade:  Nonemployer Statistics--States & MSAs by SIC   |
|RC87N3__ | 1987 Retail Trade:  Nonemployer Statistics--States, Counties,Places|
|RC87S1__ | 1987 Retail Trade:  Establishment and Firm Size--U.S.              |
|RC87L___ | 1987 Retail Trade:  Merchandise Line Sales--U.S., States, MSAs     |
|WC87A1__ | 1987 WHOLESALE TRADE:  State, Detailed Stat's--Places,Counties,MSAs|
|WC87A2__ | 1987 Wholesale Trade:  Detailed State-Total,Ratios,Bridge (old SIC)|
|WC87A3__ | 1987 Wholesale Trade:  Summary Statistics for Counties and Places  |
|WC87A4__ | 1987 Wholesale Trade:  Rankings for Counties and Places            |
|WC87S1__ | 1987 Wholesale Trade:  Establishment and Firm Size--U.S.           |
|                                                                              |
|To <R>estrict entire session to files including a particular State, press R.  |
+------------------------------------------------------------------------------+

If, based on prior experience, you expect the following file-selection menu to
include a long list of states, you may wish to use the <R>estrict option, which
prompts you to enter the 2-character postal abbreviation for the desired state. 
Unless respecified, all subsequent file selections will be limited to only those
files that include data for the specified state.
 
If, at this point, you discover that you have not correctly specified drives (or
if you have changed CD-ROMs while the program is running), you may press <ESC>
to return the previous drive-specification screen.

You may return to this menu to choose a new file at any time from the main menu,
using option 9, "Return to file selection menu".






                                                  5
Main Help Screen

The program automatically displays a general help screen which is customized to
the catalog of files you have selected.  You may wish to print it out with
<shift><PrintScreen>, and keep in handy.  This same screen can be brought up any
time you are at the main menu, by pressing <F1> for help.  (Elsewhere in the
program, the <F1> key will call up help appropriate to the screen you are in.)


Select a Database

Select any one database file.  This screen is skipped if the session has been
restricted to a particular state and there is only one file in the catalog that
qualifies.

If, at this point, you wish to return to the previous screen to select a dif-
ferent catalog, you may do so by pressing <ESC>.

+------------------------------------------------------------------------------+
|                            SELECT A DATABASE                                 |
|                                                                              |
|1. Position cursor by using <PgUp>, <PgDn>, < >, or < >                       |
|2. Press <ENTER> to select a database.                                        |
|                                                                              |
|FILE       DESCRIPTION                                                        |
|==============================================================================|
|RC87A1US | UNITED STATES by kind of business, and State and MSA totals        |
|RC87A1XS | U.S. and States by kind of business                                |
|RC87A1MM | MSAs, CMSAs, and PMSAs by kind of business                         |
|RC87A1AL | Alabama                                                            |
|RC87A1AK | Alaska                                                             |
|RC87A1AZ | Arizona                                                            |
|RC87A1AR | Arkansas                                                           |
|RC87A1CA | California                                                         |
|RC87A1CO | Colorado                                                           |
|RC87A1CT | Connecticut                                                        |
|RC87A1DE | Delaware                                                           |
|RC87A1DC | District of Columbia                                               |
|RC87A1FL | Florida                                                            |
|RC87A1GA | Georgia                                                            |
|RC87A1HI | Hawaii                                                             |
|RC87A1ID | Idaho                                                              |
+------------------------------------------------------------------------------+

After you have selected a file, the message "Reading in data dictionary" alerts
you to the fact that the system is setting up the auxiliary files for the
selected file.  Depending on the number of items in the file and the speed of
your hardware, this step can take up to a minute.










                                                  6
Main Menu                                                                       

==============================================================================
|                                                                            |
|                               MAIN MENU                                    |
|                                                                            |
|                                                                            |
|                                                                            |
|       1.  Select ITEMS                 6.  Display to Screen               |
|                                                                            |
|       2.  Select RECORDS               7.  Print                           |
|                                                                            |
|       3.  Add LABELS                   8.  EXTRACT DATA to a file          |
|                                                                            |
|       4.  Manipulate Files             9.  Return to FILE SELECTION menu   |
|                                                                            |
|       5.  Format options              10.  Advanced options                |
|                                                                            |
|                                                                            |
|           ( Q to QUIT )    ( D for Definitions )    ( <F1> for Help )      |
|                                                                            |
|                                                                            |
|                                                                +----------+|
|                           Enter option number:                 | RC87A1MN ||
|                                                                +----------+|
==============================================================================

The options on the main menu may be used in any order.  Most sessions involve--

    Option 6   a quick display to screen 

followed by several steps to refine the display, including--

    Option 1   selecting just the items (columns) you want,
    Option 2   selecting records (rows) 
    Option 3   adding text labels to each row.

Redisplaying to screen (option 6) may be done between each step to confirm that
the selections are appropriate or fit in the desired space.  Each option may be
repeated as necessary to fine tune your report.

Finally, results can be saved for future use by--

    Option 7   printing data out
    Option 8   copying selected data to a file on a floppy or hard disk for use
               with other software.

If you do not understand the difference between selecting items and selecting
records with regard to the particular file you are using, refer to the main help
screen, which can be called up by pressing <F1>.

Other options:

    D       If the message ( D for Definitions ) appears as it does above, then
            the current file has concept definitions, table locators, and
            sometimes also methodological statements accessible from the main
            menu.  Press D <enter> to display a list of all of the topics

                                                  7
            available, and select one for display using the cursor keys and
            <enter>.

    BW      Black/White.  If you find that the colors EXTRACT uses do not
            display well on your monitor, you may type BW <enter> as an option,
            and the display will revert to black and white (monochrome).  (To
            eliminate color automatically on future sessions, see the discussion
            of command line parameters on page 23.)

    SH      Show file selection criteria.  The notation is rather cryptic,
            citing codes rather than recognizable category names, but may be
            worth looking at if record selection does not work as intended. 
            Type SH <enter> to turn this feature on, or again to turn it off.


Specific Options

1) Select Items

+------------------------------------------------------------------------------+
|                             SELECT ITEMS                                     |
|                                                           (Press H for HELP) |
|Enter an X next to each item to include in display.                           |
|                                                                              |
|Use <PgUp>, <PgDn>, < >, or < > to scroll through the list.                   |
|TO EXIT: Press the <ESC> key.                                                 |
|                                                                              |
|X   FIELD NAME    DESCRIPTION                                                 |
|==============================================================================|
|  | --title---  |   1987 RETAIL TRADE:  General Statistics    RC87A1          |
|  | ST          | FIPS State Code                                             |
|  | MSA         | MSA or CMSA Code     (9999=not in MSA, 0000 in New England) |
|  | PMSA        | PMSA Code            (9999=not in PMSA)                     |
|  | COUNTY      | FIPS County Code                                            |
|  | PLACE       | Census Place Code                                           |
|  | PLACEFIP    | FIPS Place Code                                             |
|  | RECTYPE     | Record Type  (02=State,04=MSA,05=non-MSA,06=County,07=Place)|
|x | RTL87KB     | Retail Kind-of-Business Code        (001=Total Retail Trade)|
|  | ----------  |   (for text, incl. SIC code, Add Labels)                    |
|x | ESTAB       | Number of establishments, 1987                              |
|  | SALESF      |   Flag for SALES                      (0=data, 1=disclosure)|
|x | SALES       | Sales ($1,000), 1987                                        |
|  | PAYROLLF    |   Flag for PAYROLL   (0=data, 1=disclosure, 2=not available)|
|                                                                              |
|Options:<J>ump,<L>ocate,<W>ord srch,<D>efinition,<P>review,<U>ser-defined item|
+------------------------------------------------------------------------------+

This screen lists all of the items on any one record in the file.  Enter an X
next to each field you want to select into your output.  If you enter an X but
the highlighted area stays blank, you are on a comment line.  Move from item to
item with the up and down arrow keys, or move whole screenfuls at a time with
<PgUp> and <PgDn>.  To unselect an item previously selected, press the space bar
to blank out the X.

When finished, press <ESC> to return to the main menu.

For files with a long list of items, the following special keys may be useful:

                                                  8

 J  Jump to a particular field name.  After you type J, the system prompts for a
    specific field name to jump to.  Partial entries are acceptable.  The system
    will jump to the next field name that begins with the characters you
    specify.

 L  Locate a particular description.  Typing L brings up a prompt for a charac-
    ter string.  The system will then scan for the next text description
    starting with those letters.

 W  Word search.  Like <L>ocate, typing W brings up a prompt for a character
    string.  EXTRACT then presents a list of only those items where that word or
    character string is included in the description.  

Several other keys also offer special functions:

 D  Definition.  Typing D will bring up a narrative definition of the current
    item corresponding to the text that appears in appendixes to printed reports
    or documentation.  Definitions are available only for those items with a dot
    < > to the right of the field name.  If no dots are shown, definitions have
    not been prepared for this file.

 P  Preview.  Pressing P brings a box to the top of the screen that previews the
    way column headings and one data line will display in the normal columnar
    screen display (option 6 from the main menu).  The primary advantage to
    previewing rather than the regular display is that previewing is nearly
    instantaneous, while the regular data display may take some time to find all
    of the records to fill a screen.  Previewing allows you to see how many
    items fit on the screen at once, to truncate the width of any item (see the
    discussion of the W option on page 18), or R to <R>eturn to the item
    selection menu to delete previously selected items or add new ones. 
 
 U  User-defined items.  Typing U displays the box illustrated below for
    specifying a user-defined item.  You may specify a ratio or percent (nume-
    rator, denominator and scaling factor) or a freeform expression (e.g., the
    sum of several items or a string function on a character variable).  You may
    define up to 10 user-defined items.  In data displays, user-defined items
    are displayed at the right, after all other selected items.  User-defined
    may be printed out or extracted to a file, but they cannot be used as record
    selection criteria.  

+-User Defined Item------------------------------------------------------------+
|          Numerator                    /   Denominator        * Scaling Factor|
|Ratio:    sales*1000                       estab                   1          |
|  --OR--                                                                      |
|Freeform expression:                                                          |
|    Field Name   Description                Length:  8     Decimal places:    |
|    SalesEst     Sales per establishment ($), 1987                            |
+------------------------------------------------------------------------------+

    Ratios:  Typical applications include the computation of percents (make the
    scaling factor 100) or population per square mile (scaling factor is 2590 to
    convert thousandths of a square kilometer to square miles).  In the example
    of sales per establishment below, SALES*1000 is entered rather than just
    SALES to compensate for the fact that sales are reported in thousands of
    dollars.


                                                  9
    Field names must be specified exactly as they appear in the data dictionary
    or in the column headings, except that upper and lower case do not matter. 
    Items added as labels from another file (see below) may be included in a
    computation if correctly specified, e.g., COUNTY->POP87, as can previously
    specified user-defined items.

    Freeform expressions:  These may be dBase-compatible expressions either
    numeric or character in type.  To enter one, you must skip past the
    numerator, denominator, and scaling factor fields (press <enter> three
    times).  The sum of a series of consecutive fields may be entered in the
    form E50_99:E1000P, which, in the Location of Manufacturing Plants files, is
    equivalent to E50_99 + E100_249 + E250_499 + E500_999 + E1000P, or total
    establishments with 50 or more employees.  This procedure should not be used
    if there are intervening flags or other variables.  

    Examples of character-type free-form expressions include ST+COUNTY, con-
    catenating the 2-character ST code with the 3-character COUNTY code, or
    SUBSTR(GEOTEXT,1,10) if you want to copy to an extract file only the first
    10 characters of GEOTEXT.

    Other notes:  To be accepted, field names entered must be spelled correctly,
    but upper and lower case are not significant.  The "Field Name" of a
    previously computed user-defined item may be used in lieu of repeating the
    same terms in a subsequent user-defined item.


2) Select Records

+------------------------------------------------------------------------------+
|SELECT RECORDS                                                                |
|                   Mark with S the variable(s) to restrict.                   |
|                ( you will be prompted for values to select )                 |
|                                                                              |
|TO EXIT: Press the <ESC> key.                                                 |
|Use <PgUp>, <PgDn>, < > , or < > to scroll through the list.                  |
|                                                                              |
|S   FIELD NAME    DESCRIPTION                                                 |
|==============================================================================|
|  | --title---  |   1987 RETAIL TRADE:  General Statistics    RC87A1          |
|  | ST        * | FIPS State Code                                             |
|S | MSA       * | MSA or CMSA Code     (9999=not in MSA, 0000 in New England) |
|  | PMSA      * | PMSA Code            (9999=not in PMSA)                     |
|  | COUNTY    * | FIPS County Code                                            |
|  | PLACE     * | Census Place Code                                           |
|  | PLACEFIP  - | FIPS Place Code                                             |
|  | RECTYPE   * | Record Type  (02=State,04=MSA,05=non-MSA,06=County,07=Place)|
|  | RTL87KB   * | Retail Kind-of-Business Code        (001=Total Retail Trade)|
|  | ----------  |   (for text, incl. SIC code, Add Labels)                    |
|  | ESTAB       | Number of establishments, 1987                              |
|  | SALESF      |   Flag for SALES                      (0=data, 1=disclosure)|
|s | SALES       | Sales ($1,000), 1987                                        |
|  | PAYROLLF    |   Flag for PAYROLL   (0=data, 1=disclosure, 2=not available)|
|                                                                              |
|*  Marked variables are indexed, - denotes others with value selection menus  |
+------------------------------------------------------------------------------+



                                                 10
To select records (i.e., to restrict the types of rows displayed), you may
select on the values of any of the fields in the database.  Most frequently,
this involves selecting on a geographic code (e.g., ZIP code, county) or other
identifier (e.g. a kind-of-business code).  You may also select based on values
of data fields, e.g. records with a value greater than 100 in the ESTAB field.

The screen presents you with the same list of variables as before under item
selection, but this time you enter an S next to the one or two variables on
which you wish to be prompted for specific selection criteria, which the program
will do after you press <ESC>.  (You may move among variables using the cursor
keys, or with <J>ump, <L>ocate, and <W>ord Search, as described under Select
Items above.)

You may select on either one or two variables at the same time.  To select on
two variables, for example, records showing at least $10,000,000 in sales within
the Minneapolis-St. Paul MSA, enter an S next to both MSA and SALES.  The
program will prompt for criteria for each variable in turn.

The record selection dialog continues in two different ways depending on whether
or not a menu of possible values is available.  Field names with either an
asterisk (*) or dash (-) next to them generally have menus available.

    Selecting codes from a list.  If you are selecting based on a code
representing geographic areas, kinds of business, commodities, or other clas-
sifications, you will be prompted with the names of each category.  The number
of entries you may select is limited to 17, or fewer if you are selecting based
on more than one variable.

+------------------------------------------------------------------------------+
|SELECT RECORDS  (Screen 2)                                                    |
|                                                                              |
|Enter an X next to each value you want to include.                            |
|                                                                              |
|Use PgUp, PgDn, and ARROW KEYS to scroll through the list.                    |
|TO EXIT: Press the <ESC> key.                                                 |
|                                                                              |
| X   MSA          DESCRIPTION                                                 |
|==============================================================================|
|   | 5040       | Midland, TX MSA                                             |
|   | 5082       | Milwaukee-Racine, WI CMSA                                   |
|   | 5082       |   Milwaukee, WI PMSA                                        |
|   | 5082       |   Racine, WI PMSA                                           |
| x | 5120       | Minneapolis-St. Paul, MN-WI MSA                             |
|   | 5120       |  MN part, Minneapolis-St. Paul, MN-WI MSA                   |
|   | 5120       |  WI part, Minneapolis-St. Paul, MN-WI MSA                   |
|   | 5160       | Mobile, AL MSA                                              |
|   | 5170       | Modesto, CA MSA                                             |
|   | 5200       | Monroe, LA MSA                                              |
|   | 5240       | Montgomery, AL MSA                                          |
|   | 5280       | Muncie, IN MSA                                              |
|                                                                              |
|To select based on range of codes, type R.   Other options: D, J, W, or H<elp>|
+------------------------------------------------------------------------------+

Scrolling through the list is accomplished with the up and down arrow keys,
<PgUp> and <PgDn>.  You may go directly to the bottom of the list with
<Ctrl><PgDn> or back to the top with <Ctrl><PgUp>.

                                                 11

Several other keys offer special functions:

 D  Definition.  Typing D will bring up a narrative definition of the current
    category, if available.

 J  Jump to a particular code.  After you type J, the system prompts for a
    specific code to jump to.  If, in the above example, you had known that the
    code you wanted was somewhere around 5000, jumping to that code would have
    saved a lot of scrolling through the list.

 L  Locate a particular description.  Typing L brings up a prompt for a charac-
    ter string.  The system will then scan for the first description starting
    with those letters.  For example, in the illustration above "Mo" would bring
    Mobile to the top of the display.  

 R  Range specification.  If you want to specify a long series of contiguous
    codes, you may elect to enter them as a range of codes, described below.

 W  Word search.  After you type W, the system prompts for a word or any other
    string of characters.  EXTRACT then presents a list of only those codes
    where that word or character string is included in the description.  One
    application is in assembling a list of all metropolitan areas in a state. 
    Entering WI as the search word would bring up a list of all descriptions
    including those characters, including all Wisconsin metro areas and also
    some other titles with "Wi" or "wi" in them, like Wichita.  At this point
    you may simply select those you want and ignore those where "wi" does not
    appear as a state abbreviation.  Executing a word search can be very time
    consuming with long code lists, like foreign trade commodity codes.

    Selecting a range of values.  If you are selecting records based on a data
value (e.g., only records showing sales more than $10,000,000), on a code
without names, such as a ZIP Code, or have exited from the code selection screen
above with an "R", you will be prompted to enter the lowest and highest values
you wish to select.

================================================================================
| SELECT RECORDS--by specifying a range                                        |
|                                                                              |
| Enter MINIMUM value for SALES     :  10000                                   |
|                                                                              |
| Enter MAXIMUM value for SALES     :                                          |
================================================================================

This example selects all values greater than 10,000 ($10,000,000 since sales
figures are expressed in thousands of dollars); 10,000 is entered as the minimum
value, and nothing is specified for the maximum value.  Selecting all values
less than or equal to a given amount can be accomplished by leaving the minimum
value blank and entering the amount as the maximum.

To select only a single value, e.g. an ZIP Code of 22012, enter that value as
both the minimum and maximum.

    Picking the best record-selection variables.  In the first record-selection
screen, illustrated on page 9, some field names have an asterisk (*) next to
them.  These variables are featured in dBase "index files" that can help
software locate desired records very quickly.  When selecting records in large

                                                 12
files it is highly desirable to include one of the asterisked variables in
search criteria.  For example, in the illustration above, there are two codes
for places:  PLACE and PLACEFIP.  Only PLACE has an asterisk, and this is the
variable you should use if you want to search for a particular place in this
file.

Many Census Bureau files feature data for multiple levels of geography, e.g.,
states, metropolitan areas, counties and places.  These levels are differen-
tiated in economic census files by the variable RECTYPE, and in 1990 census
files by the variable SUMLEV.  When selecting data for all counties, the novice
user may be tempted to use the variable COUNTY and then proceed to check off as
many values for the county code as possible.  This will select all records with
those county codes, but that may include not only records for counties, but also
for places and other units of geography within the marked counties.  To dif-
ferentiate counties from other geographic levels, the user should select
counties as a type of record (RECTYPE value "06") or summary level (SUMLEV value
"050").  One useful rule of thumb is that if you use the word "all" in describ-
ing your query (e.g., all metropolitan areas, all places within a particular
county, all block groups within a selected tract), then you probably need to use
RECTYPE or SUMLEV, either alone or in combination with another code.

Where selection criteria are not related to available indexes, e.g., selecting
records based on the volume of sales or number of employees, the program will
operate more slowly than otherwise, examining every record in the entire data
base for "hits", a time-consuming process.  Scanning every record of a database
on CD-ROM can take up to 5 minutes per megabyte.  Just be patient.

    "Speed up retrieval" prompt.  In certain record selection scenarios, the
system may prompt you to select a value within an additional variable.  In
selecting records for the Minneapolis-St. Paul MSA, for example, the system
responds by prompting you to also select a single value for record type, as
illustrated below.  This is because the index is sorted by MSA within record
type (which keeps MSA total records separate from those county and place records
that also include MSA codes.)  

+------------------------------------------------------------------------------+
| +--------------------------------------------------------------------------+ |
| | YOU MAY SPEED UP RETRIEVAL . . .                                         | |
| |   by entering an X next to ONE code for RECTYPE, then pressing <ESC>     | |
| +--------------------------------------------------------------------------+ |
|     Press <F1> or H for Help.  Press <ESC> to skip.                          |
|Use <PgUp>, <PgDn>, < >, or < > to scroll through the list.                   |
|                                                                              |
|  X   RECTYPE   DESCRIPTION                                                   |
|==============================================================================|
|    | 02      | State                                                         |
|  x | 04      | Metropolitan Statistical Area                                 |
|    | 05      | Nonmetropolitan part of State                                 |
|    | 06      | County                                                        |
|    | 07      | Place                                                         |
+------------------------------------------------------------------------------+

In many cases, the selection you make here does not in fact reduce the scope of
your query.  The system merely uses the index to find an appropriate place to
start in the database, then discards the index.  Thus, if you are not sure which
code to pick, at least make sure that you pick one that is valid in combination
with the selection criteria you have already given.  For example, if you were to

                                                 13
check code 02 for State in this example, no records would be found because state
records never have MSA codes other than 0000.

    Other notes on record selection.  The program works best when selection
criteria isolate adjacent records.  For example, a request for a single county
or list of counties with adjacent codes can be retrieved faster than a list with
codes that are not adjacent.  If the desired records are widely separated in a
large file, e.g., MSA data for Abilene and Wichita Falls, it will probably be
faster to make two separate queries than to check off both codes in a single
query.  Even if you want the results in a single output, you can make two
separate retrievals, save them to DBF files, and then merge them "vertically"
into a single data set, as discussed under "Advanced Topics", below.

If only one value is selected, the description for that code will appear as a
second-level heading, without the need to add labels for that code.

For specialized inquiries, it is possible to enter a dBase style conditional
expression instead of working through menus for record selection.  This option
is discussed under "Advanced topics" at the end of the document.

Except for those conditional expressions, the items that you use in the record
selection process must be in the current file.  If you want to select records
based on a user-defined item (e.g., population per square mile) or on an item or
label merged from another file, you must first create an extract file including
those items in .DBF format, load that file, and then make your selections.

You may return and reselect records at any time, and the new criteria will
simply supersede the old.  To cancel previous selection criteria, bring up the
first record selection screen and press <ESC>.  If, after bringing up that
screen, you decide that you do want to <R>einstate the previous selection
criteria, press <R> before pressing <ESC>.  <R>einstating previous criteria also
can be used to specify a third and fourth selection variable, as discussed under
"Advanced Topics".  (If you have already gone on to Select Records Screen 2, it
is too late to <R>einstate previous criteria.)
























                                                 14
3) Add Labels

This option can be used to add titles or names for code variables, such as
geographic names, kind-of-business codes, etc., to displays or extract files. 
(If you have not done so already, the system will prompt you to select items
first before adding labels.)  In some cases there may be no text labels avail-
able.

==ADD LABELS=================================================================
|                                                                           |
|   Use < > or < > to position cursor on a code for which you want labels   |
|   Hit <ENTER> key to select                                               |
|   Hit <ESC> key for no labels                                             |
|                                                                           |
| CODE         Code field for which labels are available                    |
| ==========================================================================|
| ST         | FIPS State Code                                              |
| MSA        | MSA or CMSA Code     (9999=not in MSA, 0000 in New England)  |
| PMSA       | PMSA Code            (9999=not in PMSA)                      |
| COUNTY     | FIPS County Code                                             |
| PLACE      | Census Place Code                                            |
| PLACEFIP   | FIPS Place Code                                              |
| RECTYPE    | Record Type  (02=State,04=MSA,05=non-MSA,06=County,07=Place) |
| RTL87KB    | Retail Kind-of-Business Code        (001=Total Retail Trade) |
=============================================================================

Move the cursor down to highlight the desired label variable, then press
<ENTER>.

The system then presents you with a Screen 2, listing the different variations
of the label available, generally differentiated by the width to be occupied. 
Shorter labels are usually preferred in columnar reports due to space con-
straints.  Longer labels are generally more descriptive, and should generally be
used with the rowwise report (see Format Options, below).  To select one,
highlight it and press <ENTER>.

==ADD LABELS=================================================================
|                                                                           |
| ==ADD LABELS  (Screen 2)=====================================================
| |      Select one of these variations of the label.                         |
| |           Use < > or < > to position cursor on desired label.             |
| |           Hit <ENTER> key to select.                                      |
| |                                                                           |
| | CODE         Description of available labels                              |
| | ==========================================================================|
| | TEXT       | SIC code(s) and description, abbreviated to 60 characters    |
| | TEXT10     | SIC code(s), abbreviated to 10 characters                    |
| | TEXT20     | Description, abbreviated to 20 characters                    |
| | TEXT40     | SIC code(s) and description, abbreviated to 40 characters    |
| | TEXT5      | Unique mnemonic based on sic code                            |
==|            |                                                              |
  |            |                                                              |
  =============================================================================
  Press A to show all fields (not just labels).    Press M for multiple labels.




                                                 15
Special options for Add Labels Screen 2:

 A  Show All fields.  Some label files have more to offer than just text labels. 
    For example, a file with state or county names may also have population
    estimates.  A file of commodity titles may have cross-links to other coding
    systems.  Screen 2 normally displays only those options beginning with the
    letters "TEXT".  Typing A will cause all fields to display.

 M  Multiple labels.  If you want to add more than one field from this set of
    labels, for example, both the state name and population, you must type M
    before selecting the first label in Screen 2.  Thereafter, you may select
    any label by highlighting it with the up or down arrow and pressing <ENTER>. 
    Unlike the normal mode, however, the Add Labels Screen 2 will remain, with a
    ">" next to the selected label.  You may continue selecting labels, up to 10
    from any one source.

 J  Jump to a particular field name.       | These three functions operate here
 L  Locate a particular description.       | as do under Select Items.  See page
7.
 W  Word search.                        |

It is also possible to select labels from two different sources, e.g., for both
kind of business and county, at the same time.  This is not always advisable,
though, since two sets of labels may take up too much space on the screen, and
because keeping track of two sets of labels slows down most data retrieval
operations.  A second set of labels is frequently unnecessary.  If records have
been selected based on a single code value, e.g., a particular kind-of-business,
the description of that value will appear automatically on screen displays and
printouts as a second-level heading.  If you are merging data horizontally (see
"Advanced Topics" below) you are limited to using labels from only one source.

To select a second set of labels, select "Add Labels" a second time from the
main menu.  At the first screen, a blinking message at the top will prompt you
to type "S" in order to save the first set of labels, before you select the
second set.  If you do not type "S" when prompted, the new selection will
replace the earlier labels.

Long labels may be shortened with the <W>idth option discussed under "Display to
Screen", and also available in the Preview mode of the Select Items screen.

4) Manipulate Files

The Manipulate Files menu offers a number of ways to resequence output, combine
it with data from other files, or reduce the data by generating totals.

    1.  Select an existing index
    2.  Create a new index
    3.  Merge files horizontally (add items to existing records)
    4.  Merge files vertically (add more records to existing file)
    5.  Create totals or subtotals

Use of these options requires somewhat greater understanding of database
concepts than do most of the other features of EXTRACT.  Therefore, their
discussion is deferred to "Advanced Topics" near the end of this document.




                                                 16
5) Format Options

+------------------------------------------------------------------------------+
|                                 FORMAT OPTIONS                               |
|  Type of report                                                              |
|                                                                              |
|1 Select columnar output  X                                                   |
|2 Select row-wise output                                                      |
|                                                                              |
|3 Heading (1st level)     1987 RETAIL TRADE:  General Statistics    RC87A1    |
|4 Heading (2nd level)   Minneapolis-St. Paul, MN-WI MSA                       |
|                                                                              |
|  Configure output for printer          Current values                        |
|                                        --------------                        |
|5 Page width                                  80                              |
|6 Number of data lines per page               60                              |
|7 Top margin                                  0                               |
|8 Left margin                                 0                               |
|9 Print one page at a time                    NO                              |
|                                                                              |
|  Press <ESC> to return to main menu                                          |
|                                                                              |
|                                                                              |
|  Enter option number : 3                                                     |
|                                                                              |
|  Enter heading 1:    1987 RETAIL TRADE:  General Statistics   (J.Doe 9/1/91) |
+------------------------------------------------------------------------------+
 
There are two basic types of format options.  The selection of columnar or
rowwise output and the specification of headings affects all subsequent output
to the screen, printer or extract file.  Page length, page width, margins and
print mode are settings which affect only printer output.  Columnar and rowwise
output are discussed under "Display to Screen" below.

Certain headings are provided as defaults.  The data dictionary supplies the
default first-level heading; selecting records with a single code will introduce
the label for that code as a second-level heading.  Either default may be
overridden here.  Entering either "3" or "4" will bring up that label for
editing.  You may insert or delete words, or you may start fresh by typing
<Ctrl>Y to clear the prompt area.  The example above illustrates how the heading
can be used to document not only the data but also your name and date, to help
you keep your printouts straight.  Note that the second-level heading will be
overwritten by the program every time you reselect records.

To change the bottom margin change the number of data lines per page.

Page width can be set for any amount, for instance, 136 for compressed print or
wide carriage printers.  This option affects only the number of characters
generated per line, not the font or spacing on your printer.  EXTRACT does not
change printer settings, e.g., compressed print, but if you have a small utility
program that does so, you may call it from the Advanced Options menu (see
page 23).  If the number of data items you specify requires more than the
specified page width, printed output will wrap to the next line (unlike output
to the screen where the columns that do not fit simply do not show up until you
cursor to the right or left).  For a neater printed display, you will have to
return to the item selection screen and delete some of the items you intended to
display, or reduce the width of certain columns (see "Display to Screen" below.)

                                                 17


6) Display to Screen

    Note, on execution speed.  If you are working with very large files on
    CD-ROM, and if you are selecting records based on criteria not related
    to an available index file, the program may take a number of minutes to
    set up the data display.  The program does not return control to you
    until a screenful of data is displayed, and if only a few records meet
    the criteria you set, the program may continue looking to the end of the
    file for more.  

    Columnar display.  In columnar reports, the normal presentation, information
is displayed in columns (for each data item) and rows (for each record).  While
only a limited number of columns and rows can be displayed at any one time, you
may think of the display as a window into a larger worksheet, since you may
cursor to the right to see additional items, or down to see more records.

The initial display of data from some files may seem unfriendly if no text
labels are present.  In the illustration below, a number of code fields appear
first (on the left side) in each record (row), and some of the data items we are
interested in, e.g., sales, are off the screen.  The illustration on the next
page shows the same data set after we have selected items, selected records,
added labels, and added a heading, as discussed elsewhere in this documentation.

+------------------------------------------------------------------------------+
|Use ARROW keys to scroll up, down, and sideways.       Press ESC when finished|
|                                                                              |
|                1987 RETAIL TRADE:  General Statistics    RC87A1              |
|  ST   MSA    PMSA   COUNTY   PLACE   PLACEFIP   RECTYPE   RTL87KB   ESTAB    |
|==============================================================================|
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 001     |   27005  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 007     |    1876  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 008     |     908  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 009     |     736  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 010     |     172  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 011     |     697  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 012     |     203  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 013     |      68  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 014     |     591  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 016     |     152  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 023     |     152  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 028     |      32  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 029     |      87  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 030     |      33  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 031     |     147  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 032     |     292  |
|  27 | 0000 | 0000 | 000    | 0000  | 00000    | 02      | 036     |    3022  |
|                                                                              |
|FIPS State Code                                                               |
+------------------------------------------------------------------------------+

Above the double line are the variable names assigned in the data base.  To see
a more complete description of the data item, move the cursor (highlighted box)
to the desired column, and the appropriate description will appear at the bottom
of the screen.  


                                                 18
+------------------------------------------------------------------------------+
|Use ARROW keys to scroll up, down, and sideways.       Press ESC when finished|
|                                                                              |
|             1987 RETAIL TRADE:  General Statistics    (J.Doe 9/1/91)         |
|                        Minneapolis-St. Paul, MN-WI MSA                       |
|RTL87KB->TEXT40                            RTL   ESTAB    SALES       SalesEst|
|==============================================================================|
|        Retail Trade                     | 001 |  13311 |  16762012 |  1259260|
|52      Bldg materials & garden supply   | 007 |    687 |   1038660 |  1511878|
|521,3     Bldg materials & supply stores | 008 |    290 |    796066 |  2745055|
|521         Lumber & bldg material dlrs  | 009 |    205 |    735569 |  3588141|
|523         Paint, glass, & wallpaper st | 010 |     85 |     60497 |   711729|
|525       Hardware stores                | 011 |    257 |    137758 |   536023|
|526       Rtl nurseries, lawn/garden sup | 012 |    105 |     88549 |   843324|
|527       Mobile home dealers            | 013 |     35 |     16287 |   465343|
|53      General merchandise stores       | 014 |    226 |   2374716 | 10507593|
|531       Dept. stores (incl. leased dp) | 016 |     80 |   2188192 | 27352400|
|531       Dept. stores (exc. leased dep) | 023 |     80 |   2074585 | 25932313|
|531 pt.     National chain               | 030 |     20 |    528734 | 26436700|
|533       Variety stores                 | 031 |     39 |     36078 |   925077|
|539       Misc. general merchandise strs | 032 |    107 |    264053 |  2467785|
|54      Food stores                      | 036 |   1462 |   2862076 |  1957644|
|541       Grocery stores                 | 037 |    929 |   2714757 |  2922236|
|542       Meat & fish (seafood) markets  | 042 |     72 |     33429 |   464292|
|                                                                              |
|SIC code(s) and description, abbreviated to 40 characters                     |
+------------------------------------------------------------------------------+

To move down through a long report, use the down arrow or <PgDn>.  Avoid holding
the <PgDn> key down continuously, allowing the screen to refresh at least the
first line before pressing <PgDn> again, or the system may go farther than you
want and take a very long time before filling the screen with data again.  To
jump quickly to the top of the file (or to the first selected record), press
<Ctrl><PgDn> simultaneously.  To jump quickly to the bottom of the file (or to
the last selected record), press <Ctrl><PgDn>.  

When a full screen of data is displayed, you may press <ESC> to return to the
main menu.  If the computer is still searching for the next record, it will
ignore the <ESC> until the next qualifying record or the end of file is reached.

Special options:

 D  Definition.  Typing D will bring up a narrative definition of the item
    (column) to which the cursor is pointing, if available.  If the cursor is
    pointing to a label, then a definition associated with that label will
    appear instead, if available.

 M  Mark a record.  Each time you display data, the program starts at the top of
    the file, or at the first record that meets the selection criteria.  A new
    starting place can be "marked" by typing M while the cursor is highlighting
    the desired record.  Subsequent displays, prints, or extracts will then
    start with the marked record.  To cancel the mark, either mark another
    record (e.g. at the top of the file) or select records again.

 S  Show contents of narrow column.  If you have used the W option (below) to
    make a column narrow, you may highlight the cell you want and type S to
    <S>how its entire contents.  

                                                 19

 T  Toggle to rowwise display.  See discussion below.

 W  Width of column.  To make a column more narrow, highlight that column with
    the cursor, then press W and enter the number of characters you want to
    allocate.  The width option is most frequently used to show only the first
    part of a long label (e.g., the first 10 or 12 characters of the county name
    is usually sufficient).  It can also be used to narrow data columns.  If the
    width you specify is less than the number of characters in the column
    heading, the heading will be truncated, but the full description will still
    be shown at the bottom of the screen.  Caution--if you specify a width less
    than required for the largest value in a numeric field, you will see only
    the rightmost digits, with no indication that the value displayed is
    misleading, until you type S to <S>how full contents. 

    (Strategy--since the screen refreshes after every width specification, it is
    faster to use the width option in the Preview mode within the Select Items
    screen--Option 1 from the main menu.)

    Rowwise display.  Rowwise displays are obtained by using the <T>oggle option
from a columnar display or selected through the format options (#5 at the main
menu).  They present each data item together with its complete description. 
This can be handy when displaying a long list of items for a small number of
records, as in a profile for a single area.  While the illustration below shows
only 5 lines per record, reflecting the items selected for the columnar display
above, the screen can accommodate up to 22 variables at a time.

+------------------------------------------------------------------------------+
|1987 RETAIL TRADE:  General Statistics (J.Doe--Minneapolis-St. Paul, MN-WI MSA|
|                                                                              |
|        Retail Trade                                                          |
|001                Retail Kind-of-Business Code        (001=Total Retail Trade|
|         13311     Number of establishments, 1987                             |
|      16762012     Sales ($1,000), 1987                                       |
|    1259260.16     Sales per establishment ($), 1987                          |
|                                                                              |
|52      Bldg materials & garden supply                                        |
|007                Retail Kind-of-Business Code        (001=Total Retail Trade|
|           687     Number of establishments, 1987                             |
|       1038660     Sales ($1,000), 1987                                       |
|    1511877.73     Sales per establishment ($), 1987                          |
|                                                                              |
|521,3     Bldg materials & supply stores                                      |
|008                Retail Kind-of-Business Code        (001=Total Retail Trade|
|           290     Number of establishments, 1987                             |
|        796066     Sales ($1,000), 1987                                       |
|    2745055.17     Sales per Establishment ($), 1987                          |
|                                                                              |
|<ESC> to quit, <PgDn> or < > to continue, <PgUp> or < > to back up.           |
+------------------------------------------------------------------------------+

Since rowwise format yields less data per screen or per page than columnar
reports, columnar format is more commonly used.  The two formats are used
together, as in using the columnar format to highlight the record you want to
look at, then <T>oggling to rowwise display for the labelled display of up to 22
items from that record.  Typing T at the rowwise screen then <T>oggles you back
to columnar format.

                                                 20

When a full screen of data is displayed, you may hit <ESC> to return to the main
menu.  If the computer is still searching for the next record, it will ignore
the <PgUp>, <PgDn>, or <ESC> until the next qualifying record or the end of file
is reached.


7) Print

This option sends a report to the printer, including the selected items for the
selected records.  Column headings are the same as in the display to the screen,
but, in addition, each printout includes a footer at the end which lists each
item and its description (up to 60 characters).  Rowwise reports may also be
printed.

Headings, margin settings, and the number of lines per page can be set via
Format Options (option 5 at the main menu).  See the discussion on page 15.

Printing may be aborted at any time by pressing <ESC>.

To save print output to a file, for example, so that you can use a printer
connected to another computer, see below.


8) Extract Data to a File

There are four options for type of file to extract, as well as a "dry run"
option:

1>  .DBF  Database format.  This creates a dBase III+ format file for the data
    and a data dictionary file, and will add the file to your "MY_FILES"
    catalog.  Thus the resulting file can be used for further data manipulation
    in EXTRACT as well as in dBase or compatible programs.

2>  .PRN  Comma-delimited format.  This format produces ASCII text records in
    which the text variables are enclosed in quotes, numeric fields are recorded
    without leading zeroes or blanks, and all variables are separated from one
    another by commas.  A carriage return terminates each record.  This format
    is commonly used for importing data into spreadsheets, statistical and
    graphics packages, and database software not compatible with dBase III+.

    If this option is selected, a prompt asks whether to add headers and
    footers.  This is desirable for import into spreadsheets, but not for
    database or some graphics packages, which may have problems with alphabetic
    information (e.g., the header labels) in fields reserved for numeric
    information.

    [To import a .PRN file into Lotus 1-2-3, load that program and type "/FIN"
    (for <F>ile <I>mport <N>umbers) and the name of the file.  If the .PRN file
    has been stored in 1-2-3's default subdirectory, 1-2-3 will display it in a
    list at the top so that you may select it by cursor rather than by typing in
    the filename.]

3>  .SDF  Fixed-format text.  This format is a straight ASCII text file format,
    with a carriage return at the end of each record.  The column widths can be
    determined by examining the original data dictionary in dBase.


                                                 21
4>  .TXT  Print file.  This is another type of ASCII file, but with page breaks
    and column headings.  It allows you to transport output to another computer
    for printing.  It is also the only way to save rowwise output to a file,
    since each of the three options above treat the data in columnar fashion.

5>  Dry run to estimate file size.  This option counts the number of qualifying
    records and generates an estimate of the number of kilobytes of storage
    space required to accommodate the output file and any temporary work files. 
    One useful application is where you intend to save the output to a 360-kb
    floppy disk.  If the estimated size of the data file, not counting work
    space, exceeds 360 kb, you have the opportunity to <ESC> to the main menu
    and reduce the number of items or records before attempting the extraction. 
    (If you do not know how much space is available on your disk, you may
    display a directory from the Advanced Options menu--see page 23.)  The fact
    that the "dry run" option counts the number of records may answer some
    queries by itself, such as how many areas have more than 1 million
    inhabitants.

+------------------------------------------------------------------------------+
|                            EXTRACT DATA TO A FILE                            |
|                                                                              |
| Select format for output file:                             <ESC> to exit     |
|                                                                              |
| 1  .DBF  Database format                                                     |
| 2  .PRN  Comma-delimited (for import to most other software)                 |
| 3  .SDF  Fixed-format text                                                   |
| 4  .TXT  Print file                                                          |
| 5  ----  Dry run to estimate file size                                       |
|                                                                              |
| Enter selection : 1                                                          |
|                                                                              |
|                                                                              |
| Enter drive, directory and output file name in the following format:         |
|                 drive:\directory\filename   (no extension)                   |
| : c:\work\mpls1                                                              |
|                                                                              |
| Enter description of file for your MY_FILES catalog                          |
| : Minneapolis-St.Paul MSA by kind-of-business (9/1/91)                       |
|                                                                              |
+------------------------------------------------------------------------------+

After you select the file type, the system prompts for the location of the
output in terms of drive, directory and file name.  You should not specify a
file extension, which will be added automatically by the system.  If you do not
specify a drive and directory, the file will be stored in your "work space"
directory, as discussed on page 4.

If you have specified option 1 (DBF), the system will prompt you for a descrip-
tion to be put in your MY_FILES catalog, should you want to use that output file
in EXTRACT.  The default description is taken from the headings previously
specified.  You may accept it (with <ENTER>), change it by cursoring to the
right to add or delete information, or start fresh by hitting <Ctrl>Y.

After completion of an extraction to .DBF, the system asks whether to return to
the original file for further manipulation or to load the newly created file.



                                                 22
9) Return to file selection menu

This option returns you to the opening menu to select another type of file from
the master catalog or another file within the same group.  If, during earlier
file selection, you restricted your file selections to only those for a par-
ticular state, that restriction will continue in force.  To access a .dbf file
you created in Option 8, select the MY_FILES catalog (always at the bottom of
the master list of catalogs).

To access data on a different CD-ROM or other device not specified in your
MY_FILES catalog (see below), press <ESC> at the select-a-catalog screen to
bring up the drive selection screen.  Do not change CD-ROMs while the program is
running without going through this step.


10) Advanced options.

+------------------------------------------------------------------------------+
|                             ADVANCED OPTIONS                                 |
|                                                                              |
|1.  Save format options to a parameter file.                                  |
|2.  Display secondary file                                                    |
|                                                                              |
|  DATA DICTIONARY     (.dct)                                                  |
|3.  Create (or replace) data dictionary for specific file                     |
|4.  Edit descriptions or label references in an existing dictionary           |
|                                                                              |
|  DATA FILE CATALOG   (.ctg)                                                  |
|5.  Add files to MY_FILES catalog                                             |
|6.  Edit descriptions                                                         |
|                                                                              |
|  OTHER                                                                       |
|7.  Clean out Selex.dbf and SeleDct.dbf                                       |
|8.  Edit index file catalog (.cti) descriptions                               |
|9.  Disk directory or other DOS functions                                     |
|                                                                              |
|  Press <ESC> to return to Main Menu                                          |
|                              Enter option number: __                         |
+------------------------------------------------------------------------------+

    Saving format options.  Specify option 1 if you have changed any of the
following variables from their defaults and wish future runs with the EXTRACT
program to start with their current values:
     Margins
     Page width
     Lines per page

    Editing your MY_FILES catalog.  Option 6 allows you to delete out-of-date
listings from your MY_FILES catalog, to change the descriptions, or to change
the drive location of particular files.  You will be prompted to confirm the
location of the catalog, including the drive and directory you normally specify
for "workspace", e.g, "C:\EXTRACT\WORK\MY_FILES.CTG".  To determine whether any
of the files in the list are no longer present in the directory where originally
stored, cursor to the far right.  The last column will indicate those files now
"ABSENT".  To delete an obsolete file, highlight the appropriate record and
press <Ctrl>U.  To edit the description, cursor to the right until you see the
description, then type over the old description and press <ENTER>.  To tell

                                                 23
EXTRACT that you are changing the location of a file, highlight the PATH field
and edit the drive designation.  If you are copying a .dbf file to a floppy disk
for use on another computer, copy your MY_FILES catalog to the floppy as well,
then go back into EXTRACT and edit the path field in the MY_FILES.CTG on the
floppy.

It is also possible to add files to your MY_FILES catalog.  This process is
described under "Advanced Topics" below.

    DOS functions.  Advanced option 9 allows you to display directories, perform
other DOS functions, or even run small programs without leaving EXTRACT.  Common
applications include determining whether there is enough disk space available to
accommodate a file to be extracted, deleting obsolete files to make room for new
extracts, or running a small program to change your printer configuration.  
 
ADVANCED TOPICS

Auxiliary Files and Their Functions:

    Data Dictionary Files.  <filename>.DCT.  Data dictionary files describe each
of the variables on the corresponding data file(s).  Each data dictionary file
has either the same filename as the corresponding .DBF file except that D is the
last character of the filename, or has a shorter filename so that it can serve
as data dictionary for a number of files that all start with the same characters
in the filename.  Data dictionaries are in dBase III+ format even though they do
not have the .DBF extension.  Some data dictionaries include both a .DCT file
and a matching .DBT file that carries definitions which are referenced as memo
fields from the .DCT files.  

    Label Files.  <filename>.DBF.  Label files carry text descriptors associated
with the individual values of particular variables (for example, the names of
particular kinds of business or geographic areas).  These files may also be
referred to as stub files, since they carry the text information normally found
in the stub (i.e. lefthand column) of printed tables.  Memo fields may be used
to provide longer definitions of values, in which case there is a .DBT file of
the same name.  Each label file must also have an associated index file.  The
file SELEX.DBF must be present in order for code labels to be used in the item
selection process.

    Catalog Files.  <filename>.CTG and <filename>.CTI.  Catalog files list the
files of a particular type that are available, along with a brief description of
each one.  The master catalog "master.ctg" lists the available catalogs, or
types of files, available on the device.  Files with the extension .CTI catalog
index files.  While .CTG files are compatible with dBase catalog files (.CAT), a
different extension is used so that users are not tempted to use them in dBase
without recopying them.  (DBase attempts to write new information to a catalog
in use, not appropriate for CD-ROM.)

    Program and Parameter Files.  EXTRACT.EXE is a program compiled by Clip-
perTM.  The first time it is used it gets certain parameters from
"extstart.prm", but as soon as the user exercises the option to save format
options, a new file "extract.prm" is created.

    Help Screen Files.  <filename>.TXT.  As soon as a catalog is selected, the
EXTRACT program displays a catalog-specific help screen, if present.  That same
screen can be brought up at any time from the main menu by typing "H".  These


                                                 24
help screen files have the same name as the corresponding catalog files, e.g.,
RC87A1__.txt.


Setting Up an EXTRACT Menu

Drive designations may be entered at the command line.  This is particularly
useful where multiple Census Bureau CD-ROMs are in use, at least one of which
relies on auxiliary files stored on a hard disk.  Command-line parameters allow
batch files or menuing systems to deliver the user right to the menu of avail-
able catalogs, thereby avoiding having to teach each user about drive designa-
tions on the system.  

The command line takes the following form

  EXTRACT <c, n, a> <data drive:[\directory]> <auxil drive:\directory>
    [<work drive:\directory> <master.ctg> <intro.txt>

Example:  EXTRACT cb l: c:\ccdbaux\ c:\test\ master.ctg ccdintro.txt

If no arguments are present, the system will operate as usual, prompting for
drive and directory designations.  The individual arguments are as follows

1.  <c, n, a, cb, nb, or ab>  C indicates that the data drive is a cd-rom; n
    indicates no cd-rom.  A, together with no additional arguments, puts the
    user immediately into the advanced menu, discussed below.  B, when added to
    the c, n, or a, puts the display into monochrome (black and white) mode.

2.  <data drive:[\directory]>

3.  <auxil drive:\directory>  This is normally "l:\auxil\" on CD-ROMs, such as
    the economic census discs, that have auxiliary files built in.

4.  [<work drive:\directory>]  

5.  [<master.ctg>]  Optional.  Any entry, which may include a full path designa-
    tion, overrides the normal default to a file named "master.ctg" within the
    auxiliary drive designated above.

6.  [<intro.txt>]  Optional.  Used so that a customized screen can be presented
    in lieu of EXTRACT's opening screen.

Using the <S>ave option at the opening Drive Selection screen generates a one-
line batch file saving the first five parameters, assigning a name you specify. 
EXTRACT also builds the file EXMENU.bat, listing each of the batch files you
have created, but without any description.  With your text editor, you can add
appropriate annotations to each line of the file EXMENU.bat, illustrated below.

    echo off
    echo .
    echo                   EXTRACT MENU
    echo .
    echo EX        EXTRACT with Economic or Agriculture Census discs
    echo EXCBP     EXTRACT with County Business Patterns
    echo EXEXPORT  EXTRACT with U.S. Exports of Merchandise
    echo EXIMPORT  EXTRACT with U.S. Imports of Merchandise
    echo EXCCDB    EXTRACT with County and City Data Book, 1988       

                                                 25
    echo EXUSACO   EXTRACT with U.S.A. Counties, 1992
    echo           EXTRACT with 1990 Census CD-ROMs:
    echo EXPL94      PL94-171
    echo EX1A        STF 1A
    echo EX1B        STF 1B (Block statistics)
    echo EX1C        STF 1C
    echo EX3A        STF 3A
    echo EX3B        STF 3B (ZIP Code data)
    echo EX3C        STF 3C
    echo EXEEO       EEO file
    echo on

Below are listings of the corresponding batch files, created with your text
editor or simply by using <S>ave.  This illustration assumes that the CD-ROM
drive is L:, that the subdirectory C:\EXTRACT\WORK exists for use as the
program's work space, and that the subdirectories CBPAUXIL, FTDAUXIL, CCDBAUX,
and 1990AUX within C:\EXTRACT\ contain the appropriate auxiliary files.  Note
that the fifth argument is added to specify the name of the master catalog for
foreign trade and 1990 census CD-ROMs, since each of those groups use the same
auxiliary directory.

Filename             Contents

EX.BAT              EXTRACT c l: l:\auxil\ c:\extract\work
EXCBP.BAT      EXTRACT c l: c:\extract\cbpauxil\ c:\extract\work
EXEXPORT.BAT   EXTRACT c l: c:\extract\ftdauxil\ c:\extract\work mstrexpo.ctg
EXIMPORT.BAT   EXTRACT c l: c:\extract\ftdauxil\ c:\extract\work mstrimpo.ctg
EXCCDB.BAT     EXTRACT c l: c:\extract\ccdbaux\  c:\extract\work 
EXUSACO.BAT    EXTRACT c l: c:\extract\usacoaux\ c:\extract\work
EXPL94.BAT     EXTRACT c l: c:\extract\1990aux\  c:\extract\work mstrpl94.ctg
EX1A.BAT       EXTRACT c l: c:\extract\1990aux\  c:\extract\work mstrst1a.ctg
EX1B.BAT       EXTRACT c l: c:\extract\1990aux\  c:\extract\work mstrst1b.ctg
EX1C.BAT       EXTRACT c l: c:\extract\1990aux\  c:\extract\work mstrst1c.ctg
EX3A.BAT       EXTRACT c l: c:\extract\1990aux\  c:\extract\work mstrst3a.ctg
EX3B.BAT       EXTRACT c l: c:\extract\1990aux\  c:\extract\work mstrst3b.ctg
EX3C.BAT       EXTRACT c l: c:\extract\1990aux\  c:\extract\work mstrst3c.ctg
EXEEO.BAT      EXTRACT c l: c:\extract\1990aux\  c:\extract\work mstreeo.ctg





















                                                 26
File Manipulation

+------------------------------------------------------------------------------+
|                                MANIPULATE FILES                              |
|                                                                              |
|   1.  Select an existing index                                               |
|                                                                              |
|   2.  Create a new index                                                     |
|                                                                              |
|   3.  Merge files horizontally (add items to existing records)               |
|                                                                              |
|   4.  Merge files vertically (add more records to existing file)             |
|                                                                              |
|   5.  Create totals or subtotals                                             |
|                                                                              |
|      Press <ESC> to return to Main Menu                                      |
|                                                                              |
|                                                                              |
|                                 Enter option number: _                       |
+------------------------------------------------------------------------------+

Option 1.  Select an existing index.  Some files have one or more index files
which can be used to resequence the output.  Index files can also speed certain
kinds of searches, and the "Select Records" option may pick an index for you, if
a relevant one is available.  Therefore, most users will not find it necessary
to use this option.

To explicitly select an index, highlight your selection and press <ENTER>.  To
return the file to its original sort, press <ESC>.  

+------------------------------------------------------------------------------+
|SELECT INDEX                                            (H for HELP)          |
|                                                                              |
|1. Position cursor by using <PgUp>, <PgDn>, < >, or < >                       |
|2. Press <RETURN> to select an index, <ESC> to UNSELECT.                      |
|                                                                              |
|             ndx_name   key_descr                                             |
|==============================================================================|
|             RC87C1MN | First record for each county                          |
|             RC87K1MN | By kind-of-business code, by rectype ...              |
|             RC87M1MN | First record for each MSA                             |
|             RC87N1MN | First record for each PMSA                            |
|             RC87P1MN | First record for each place                           |
|                                                                              |
+------------------------------------------------------------------------------+

Option 2.  Create a new index.  If none of the existing indexes yield the
desired sequencing, you may create a new index.  

The system prompts you to enter the key expression for the index, and, to help
you with the format, shows what the key expressions for existing indexes look
like.   The indexing expression can be as simple as "-sales" to rank all records
by sales (the leading minus sign specifies descending sequence).  To rank areas
by sales within each kind of business, the indexing expression is more compli-
cated, since alphabetic information and numeric information can only be used in
the same key after the numeric information has been converted to string format. 
The key expression shown in the illustration above subtracts sales from a large

                                                 27
number to make the descending sequence appear like ascending sequence to the
computer, converts that expression to a 10-character string, and combines it
with the kind-of-business code.  Since the spelling of variable names must be
exact, you may need to <esc> back to the main menu and review variable names on
the Select Items screen before proceeding.

+------------------------------------------------------------------------------+
|  INDEX FILE   DESCRIPTION                                INDEX KEY           |
|==============================================================================|
|  RC87C1MN   | First record for each county             | RECTYPE+ST+COUNTY   |
|  RC87K1MN   | By kind-of-business code, by rectype ... | RTL87KB+RECTYPE+ST+ |
|  RC87M1MN   | First record for each MSA                | RECTYPE+MSA+PMSA    |
|  RC87N1MN   | First record for each PMSA               | RECTYPE+PMSA        |
|  RC87P1MN   | First record for each place              | RECTYPE+ST+PLACE    |
|                                                                              |
|If the file you are working with is relatively large, and the number of       |
|records you want to access through the index is relatively small, it is       |
|likely more efficient to extract a file (.DBF) before indexing.               |
|                                                                              |
|         Enter KEY expression for new index: _______________________________  |
+------------------------------------------------------------------------------+

After you enter an indexing expression, the system prompts you for a name for
the index file and a description to enter into your MY_FILE.cti catalog of index
files.  In the future you will be able to access this index from the "Select an
existing index" option.

As the screen warns, indexes for large files can be large themselves.  All
records in the file are indexed and any previous record selection is ignored. 
Thus it may be more practical to extract the desired data to a .DBF file and
index the result than to index an entire file on a CD-ROM.


Options 3 and 4.  Merging files.  Two ways of merging files are available.  The
following illustrates the difference between vertical and horizontal merger.

    Horizontal merger:
    XXXXXXXXXXXXXXXXXXXXXXXX XXX XXXXXX XXXXXXX   XXXXXXX XXXXXXX XXXXXX
    XXXXXXXXXXXXXX--original file--XXXX XXXXXXX   XXXX--merged file--XXX
    XXXXXXXXXXXXXXXXXXXXXXXX XXX XXXXXX XXXXXXX   XXXXXXX XXXXXXX XXXXXX
    XXXXXXXXXXXXXXXXXXXXXXXX XXX XXXXXX XXXXXXX   XXXXXXX XXXXXXX XXXXXX

    Vertical merger:
    XXXXXXXXXXXXXXXXXXXXXXXX XXX XXXXXX XXXXXXX
    XXXXXXXXXXXXXX--original file--XXXX XXXXXXX
    XXXXXXXXXXXXXXXXXXXXXXXX XXX XXXXXX XXXXXXX
    XXXXXXXXXXXXXXXXXXXXXXXX XXX XXXXXX XXXXXXX

    XXXXXXXXXXXXXXXXXXXXXXXX XXX XXXXXX XXXXXXX
    XXXXXXXXXXXXXXX--merged file--XXXXX XXXXXXX
    XXXXXXXXXXXXXXXXXXXXXXXX XXX XXXXXX XXXXXXX

When you merge files horizontally, you add to your current display items from
another source that has compatible identifiers for each record.  Adding labels
is a form of horizontal merger in which the user interface is simplified by the
fact that the necessary relationships are pre-specified in the data dictionary. 
This option allows you to merge files of your own choosing, such as employer and

                                                 28
nonemployer data, data for different time periods, population and economic data,
etc.

When you merge files vertically, you append records to the end of the original
file from a second file.  Vertical merger, for instance, allows you to create a
single file that contains counties from multiple states when the original files
on CD-ROM are state-specific.

    Option 3, Merging files horizontally.  Horizontal merger takes you through
four screens, three of which are already familiar.  The first two screens--
"Select a Catalog" and "Select a Data File"-- specify the file to be merged into
the current display.  The third screen asks you on what basis the two files are
to be merged.

The simplest files to link are those that have the same number and sequence of
records (see option 1, below).  Examples include the various files within STF 1A
or within the 1988 County and City Data Book.  (Using the Add Labels option from
the main menu may accomplish the same thing with fewer steps.)  If the number of
records in the current file and new file are not the same, the system prompts
you for an expression that gives the record number in the new file, for example,
LOGRECNU (logical record number) on STF 1A files. 

+------------------------------------------------------------------------------+
|      How do records in RC87N2XS relate to records in RC87A1MN?               |
|                                                                              |
|      1. By way of the record number (e.g., STF 1)                            |
|                                                                              |
|      2. By way of an index I need to create now                              |
|                                                                              |
|      3. By way of one of the indexes listed below                            |
|                                                                              |
|                                  Enter option:  3                            |
|                                                                              |
|            INDEX FILE   DESCRIPTION                                          |
|==============================================================================|
|            RC87N2K    | By kind of business by State, MSA & PMSA             |
|            RC87N2S    | First record for each State                          |
|            RC87N2M    | First record for each MSA or PMSA                    |
|                                                                              |
|                                                                              |
+------------------------------------------------------------------------------+

The illustration above shows the linkage of statistics about employers from the
RC87A1MN file with statistics about nonemployers from the RC87N2XS file.  The
two files do not have exactly the same number of records, but they do have the
same kind-of-business, state, MSA and PMSA codes, so they can be linked by way
of the first index.  Indexes with a description "First record for..." should
normally be avoided.  Entering option 3 puts the cursor on the first index,
which is selected with <ENTER>.  That brings up the following prompt:

         Specify relation for RC87A1MN   RTL87KB + ST + MSA + PMSA             

Pressing <ENTER> here will accept the suggested relationship, which reflects the
key expression of the selected index.  Changes are appropriate if the current
file uses different names for the variables shown, or if corresponding variables
are not available.  If, for example, the link were being made from a previously
extracted file for Minneapolis-St. Paul MSA that carried the RTL87KB code but

                                                 29
did not include state or MSA codes, the relationship could be changed to
RTL87KB + "00" + "5120" where 00 is the default state code on MSA records and
5120 is the code for the Minneapolis-St. Paul MSA.  If the linking expression is
not expressed correctly, the fields merged subsequently will contain only blanks
and zeroes.

The fourth screen in the horizontal merge sequence prompts you to select items
from the new file.  

The results of this merge are illustrated below.  Data from the merged file
appear at the right, and the column headings show their source by the
"RC87N2XS->" prefix.  Note that some of the data in the righthand columns are
shown as zero.  This is because these source records had no match in the
RC87N2XS file, nonemployer data being available in less detail than employer
data.

After a horizontal merger, it is possible to combine the contents of both old
and new items in a user-defined item, for example, a freeform expression
SALES + RC87N2XS->SALES would yield total sales for employer and nonemployer
establishments.  The syntax for specifying the merged items in such an expres-
sion must be copied exactly from the headings shown.

+------------------------------------------------------------------------------+
|Use ARROW keys to scroll up, down, and sideways.       Press ESC when finished|
|                                                                              |
|                1987 RETAIL TRADE:  General Statistics    RC87A1              |
|                       Minneapolis-St. Paul, MN-WI MSA                        |
|RTL87KB->TEXT40           ESTAB   SALES      RC87N2XS->ESTAB   RC87N2XS->SALES|
|==============================================================================|
|        Retail Trade    | 13311 | 16762012 |            7346 |          309301|
|52      Bldg materials  |   687 |  1038660 |             295 |           12053|
|521,3     Bldg material |   290 |   796066 |             150 |            5686|
|521         Lumber & bl |   205 |   735569 |               0 |               0|
|523         Paint, glas |    85 |    60497 |               0 |               0|
|525       Hardware stor |   257 |   137758 |              53 |            4188|
|526       Rtl nurseries |   105 |    88549 |              72 |            2009|
|527       Mobile home d |    35 |    16287 |              20 |             170|
|53      General merchan |   226 |  2374716 |             119 |            2747|
|531       Dept. stores  |    80 |  2188192 |               0 |               0|
|531       Dept. stores  |    80 |  2074585 |               0 |               0|
|531 pt.     Conventiona |    20 |        0 |               0 |               0|
|531 pt.     Discount or |    40 |        0 |               0 |               0|
|531 pt.     National ch |    20 |   528734 |               0 |               0|
|533       Variety store |    39 |    36078 |              57 |            1482|
|539       Misc. general |   107 |   264053 |              62 |            1265|
+------------------------------------------------------------------------------+

EXTRACT does not give you control over the sequence of items in the display. 
Labels always appear first, followed by items from the current file, followed by
merged items, followed by user-defined items.

If you subsequently create an extract .DBF file or .PRN file with headings, the
system will prompt you to supply a different name and description for the
duplicate fields.  For example, you could change the field name to "ESTABnon"
and the description to "Nonemployers--Number of establishments, 1987".  The
prompt below would appear at the bottom of the Extract Data to a File screen,
and be followed by a similar prompt for the duplicate SALES field.

                                                 30

|         Duplicate field name detected                                        |
|      In original file:                                                       |
|    ESTAB      Number of establishments, 1987                                 |
|                                                                              |
|      RC87N2XS->ESTAB                                                         |
|    ESTAB_____ Number of establishments, 1987_____________________________    |
+------------------------------------------------------------------------------+

    Option 4.  Merge files vertically.  Merging files vertically involves
appending the records of a second file to the bottom of the current file. 
Unlike horizontal merger, this involves an immediate write to disk.  Therefore
the program allows you to initiate a vertical merger only when the current file
is in your MY_FILES catalog.  The file being merged in may be from any catalog,
but it is highly likely that it will also be from your MY_FILES catalog since
the entire file is read in.

The structure of the resulting file is dictated by the current, or original,
file.  Only those data fields that appear in both files with the same name will
be added in.  If there were no commonality between field names in the two files,
vertical merger would add only blank records.  Where field names are entirely
different, you may need to study horizontal merger further.

The dialog to accomplish vertical file merger is fairly short.  You are
presented with the "Select a Catalog" screen followed by the "Select a Data
File" screen, following which the merger is accomplished.  The resulting file
has the same name as it did before.  If you wish to change its description in
your MY_FILES catalog, do so with option 6 from within the Advanced Options
screen (option 10 from the main menu).

Some files may be merged either horizontally or vertically.  For example, the
nonemployer data merged in the horizontal example above could have also been
merged in vertically, since the data field names are compatible in both sources. 
Another example where a similar choice is available is data from corresponding
files for different periods of time, such as 1987 and 1982 manufactures data. 
In this case you will need to anticipate the need to distinguish the two sources
from one another in the resulting file.  This can be accomplished when creating
the original file by adding a user-defined item named YEAR and giving it a
freeform value of "87".  The records merged in from the 1982 file will be blank
in the new YEAR field.

Option 5.  Create totals or subtotals.  Totalling allows you to create a new
data base where all records with a common identifier, or totalling key, have
been summed together.  This may be an essential function in reducing the size of
certain very large files, such as imports or exports files where there are no
intermediate-level summaries that can be selected.  This function is less
frequently needed in economic census and 1990 census files where intermediate-
level totals are already included.  If your intention is to extract a file for
loading into a spreadsheet, you may well find that it is easier to defer
totalling to the spreadsheet unless, of course, you are dealing with a file too
large before totalling to be loaded into memory.

After you have entered a key expression, the system prompts for a name for the
resulting file, and a description for your MY_FILES catalog.  When the totalling
is complete, the system will prompt whether you want to return to the original
file for further work, or whether to immediately load the file you have just
created.

                                                 31
+------------------------------------------------------------------------------+
|This function creates a new database consisting of totals or subtotals from   |
|the current database.  The totals file will include all of the items (columns)|
|on this file--regardless of any subset you may have specified in SELECT ITEMS,|
|and regardless of any LABELS you may have added.  Labels can be added to the  |
|totals file, but only after this process is complete.                         |
|                                                                              |
|The prompt below asks you to specify an item or expression as the KEY.  As    |
|the program reads in new records from the file, it generates a total every    |
|time the value of KEY changes.                                                |
|                                                                              |
|The output file will contain sums for every numeric item selected (up to a    |
|maximum of 24).  Since the program will bomb if a field is not wide enough    |
|to accommodate the total generated, SELECT ITEMS to exclude flags and other   |
|numeric fields not wide enough.  For codes and other alphabetic items, the    |
|totals file will present the first value encountered within the total.        |
|                                                                              |
|Totalling can consume a lot of time and disk space.  If the number of output  |
|records will be large, and if you are interested in only a small subset of    |
|items, it may be advantageous to extract a file first and then perform the    |
|totalling on that.                                                            |
|                                                                              |
|         Enter KEY on which to total:                                         |
|                                                                              |
|MSA = 5120 to 5120                                                            |
+------------------------------------------------------------------------------+

You will get the results you want only if the records to be totalled are
consecutive.  If not, you probably need to first create a new index (option 2 on
the Manipulate Files menu--the indexing key is likely the same as your planned
totalling key).

How to Select Records with Conditional Clauses 
 
While record selection by way of the 2-level menus works well for most uses, 
those familiar with dBase may occasionally prefer to specify conditional clauses
directly.  This is possible by typing C when the first record selection menu is
presented, whereupon the prompt "Enter conditional expression:" appears at the
bottom of the screen.  What you enter at this point becomes the argument for the
dBase-style expression SET FILTER TO.  Sample entries include --  
     SALES >= 10000 
     MSA = "5120" .and. RECTYPE = "04" 
     RECTYPE = "02" .or. RTL87KB = "001" 
     IIF(ESTAB>0,SALES/ESTAB,0) >= 10000 
Note that when entering desired values for code fields stored as character
variables, they must be enclosed in quotes. 
 
While the first two examples could be entered easily by way of the menu system,
the last two examples illustrate conditions that can only be specified in this
way.  The Select Records menu system assumes that conditions set for two
variables are additive, i.e., they would be connected by a Boolean ".and.".  The
third example shows the use of an ".or." condition, in this case selecting all
state level records (RECTYPE = "02") but only those records at other levels that
are for trade area totals (RTL87KB = "001").  

The last example illustrates the selection of all records with more than
$10,000,000 (10000) in sales per establishment.  Note, however, that it was

                                                 32
necessary to imbed that SALES/ESTAB fraction within an "immediate if" (IIF) to
make sure that the program does not attempt to divide by zero when it encounters
a record where the number of establishments is zero (e.g., not available).  One
of the major pitfalls of directly entering conditional expressions is that an
error in punctuation or logic may lead to abrupt program termination.  

Record selection by way of conditional expressions does not take advantage of
indexes that may speed many of the code searches using the normal menu approach. 
You may be able to get around this problem by selecting records in two "passes". 
To select records in the Minneapolis-St. Paul MSA with at least a certain ratio
of sales per establishment, select the MSA on the first pass through select
records, then select records again, this time entering R to <R>einstate the
previous selection criteria before typing C to specify the <C>onditional
expression.

Note that the program expects you to enter the conditional clause without the
words FOR or WHILE that you might use in dBase.

Displaying Secondary Files  

The Advanced Options menu option 2--"Display secondary file"--allows you to look
at another data file without losing your place in the main file selected.  This
is a "no-frills" display, with no item descriptions from a data dictionary, no
ability to alter column width, and no ability to select items or records.  This
screen does allow rudimentary editing of the data file, including record
insertion and deletion, assuming the file is not on a CD-ROM.  Following are a
few examples of ways you may use this option.

    Checking a previously created extract file.  In the middle of setting up a
    data extraction, you may wish to refer to a file you previously created, for
    example, to include the same statistics.

    Checking a code list.  You can generally view the labels corresponding to
    particular codes by using the Add Labels function or by going through record
    selection.  If either of those approaches would disrupt the way you have
    your main file set up, you may display the label file through this option. 

    Deleting selected records.  1990 census STF CD-ROMs have multiple records
    for a particular area within certain summary levels, each defined by a dif-
    ferent GEOCOMP code.  In order to get rid of the extras, the easiest way may
    be to create an extract file (DBF format), load it with this option, point
    to the second in each group of apparently duplicate records, then delete it
    by pressing <Ctrl>U, and repeat as necessary.  If you previously created any
    indexes for this file from the Manipulate Files menu, you will need to redo
    them if you have deleted or inserted records.

    Editing particular fields.  You may change the data in a field, for example,
    to make your own annotation to an area name, by pressing <enter> to start
    the edit mode, typing over the existing contents, and pressing <enter> again
    to complete the edit.  This can be tedious if more than a few records are
    involved.

How to Get EXTRACT to Work with Other dBase Files

While EXTRACT was primarily designed to work with files as issued by the Census
Bureau, it is possible to add other dBase III-compatible files to your MY_FILES


                                                 33
catalog and to create data dictionaries for them, as a prelude to being able to
merge these data with data you have derived from census files.  

From the Advanced Options menu, Option 5 confirms the name and location of your
MY_FILES catalog file, then prompts you to <A>dd to or <R>eplace your existing
catalog.  Replacing wipes out any previous entries in the MY_FILES catalog.  The
next prompt is to "Enter full filename or mask", to which you should respond
with a filename in the form "c:\dbase\mydata.dbf" or "c:\census\*.dbf".  Both
"?" and "*" can be used in DOS wildcard expressions.  EXTRACT adds each file
name that fits that directory mask to the catalog, and then displays the catalog
entries to the screen.  Cursor to the right until you see the "title" field,
then enter whatever descriptive statement will be useful to you in the future. 
If you have accidentally added files that do not belong in the catalog, delete
them with <Ctrl>U.  

If the system cannot find a data dictionary for each file added to the catalog
(it looks in the default directory and in the same directory as the data file
for a data dictionary that may have been created previously), EXTRACT will
create one, asking you to specify a directory location for the .DCT file. 
Unless you specify otherwise, it will put it in the same directory as the data. 
  
In order to create a data dictionary, the system will ask for the full name of
an existing dictionary files that it can use as a pattern--i.e., a .DCT file
that already exists in the \AUXIL subdirectory on the CD-ROM or in an auxiliary
directory installed on your hard disk.  If you specify a .DCT file with any
field names that are the same as field names in new .DBF file, the program will
copy their descriptions to the new dictionary, saving you the trouble.  

The program then presents you with the field names and spaces to fill in
descriptions.  You must press <ENTER> after you have edited any field in order
to move on to the next field.  After you enter all of the 60-character descrip-
tions and press <ESC>, the program will prompt you for 40- and 20-character
descriptions, which you may skip if you wish.  The final set of prompts is for
entries to fields called LABELFILE, LABELNDX, LABELKEY, and ALTNAME, which, if
applicable, the program will have already picked up from the pattern .dct(s).  

If the data file you are adding to the catalog is not one you are familiar with,
you may find that you are not confident of the descriptive titles you are
entering for files and variables.  Rest assured that you can return to the
Advanced Options menu at any time to further edit the titles in your MY_-
FILES.CTG (Option 6) or in the data dictionaries you have created (Option 4).

These procedures do not attempt to create label files for databases created
outside of EXTRACT.  If you want to do so in dBase III, adapt the structure of
one of the label files on CD-ROM insofar as is possible.

Miscellaneous Notes

If you find that you are not able to move up or down or side to side on screen
displays, check to make sure that your NumLock key has not been set on.

The program can be aborted at any time by pressing <Alt>C, and answering No to
the question displayed at the top of the screen.  Aside from <Ctrl><Alt><Del>,
this may be the only way to regain control of the computer if the system is
doing a search that is taking so long that you lose interest.



                                                 34

NOTES ON THE USE OF EXTRACT WITH SELECTED CENSUS BUREAU CD-ROMS

1987 Economic Census Discs, Volumes 1 and 2

Auxiliary files needed by EXTRACT are on each disc.  Each successive disc within
each volume supersedes the previous disc.  For example, Disc 1d includes all
files from Disc 1a, 1b, and 1c, plus many more; Disc 1d also corrects a few
minor errors in Disc 1c.  Supplementary files have been issued on the Census
electronic bulletin board (BBS) (see Getting Assistance, below) that address
errors on CD-ROMs 1d and 2b.

Most data files contain no text labels, but there are state, county, and place
names built into the "A3" and "A4" files for retail, wholesale, services, and
transportation, and the "A1" files for manufactures.  For other files, simply
"add labels".

Most data dictionaries and label files have definitions available that can be
displayed from the main data display screen or during item or record selection.

Some of the Manufactures Industry Series files have separate footnote files for
footnotes that are specific to particular data cells.  To display them in a
manner that actually mimics footnotes, select the footnote files with the "Add
labels" command, use the <W>idth option in the Display or Preview mode to limit
them to a single character in width, then press S to <S>how the entire footnote
when the one-character column is anything other than blank.

Many of the auxiliary files on the Volume 1 discs are useful data files in their
own right.  For instance, the STCOUNTY.dbf shows not only county names and
codes, but also population estimates for the last three economic census years--
1987, 1982, and 1977.

Record selection

Many of the files in Volume 1 feature data for multiple levels of geography,
e.g., state, metropolitan areas, counties and places.  Selecting records for a
particular county will bring up all records with that county code, which
includes places within that county as well as the county total.  Thus, to bring
up only county total records for a particular county, select on both RECTYPE,
checking off code "06" for counties, and COUNTY.  To view data for all counties,
select only on RECTYPE.

Record selection by place code brings up a code list that includes counties as
well as places, county records having a place code of "0000".  Simply <PgDn>
until you come to the place records, which will have nonzero codes.

After specifying record selection, EXTRACT may prompt you to enter a value
within one or more additional variables in order to speed the search.  Most
commonly the request is for a single value for record type, since many of the
indexes which can speed the search involve record type.  When selecting records
for a particular county within the RC87A3, WC87A3, and SC87A3 files, you will be
prompted to select single values within record type, state, and place--due to a
quirk in the structure of the available index.  Since you probably do not want
to select only a single record type or place, press <ESC> to when prompted to
check off one of their values.  



                                                 35
1987 Census of Agriculture--State and County Data

Auxiliary files needed by EXTRACT are on this disc.  On the other hand, the
Agriculture Specialty Publications CD-ROM consists primarily of files in Lotus
1-2-3(tm) and flat ASCII formats, and is not accessible with EXTRACT.

The "definition" function is not available on the Agriculture State/county disc,
since narrative definitions were not built into the dictionary and label files.

Note that the ZIP code data from the census of agriculture are available on
Economic Census CD-ROM 2b, along with ZIP code data from the censuses of
manufactures, retail trade, and service industries.

Adding labels

There are no text labels in the county files.  To describe a particular data
record in these files you need to identify both the county and the item number. 
EXTRACT gives you the capability to add up to two sets of labels at a time,
e.g., both county labels and item labels, but that will leave you without enough
space for data in the columnar display unless text columns are truncated with
the <W>idth function.  Two sets of labels also slows down all data retrieval
operations.

The most common inquiries, though, look for a number of items for a given county
or all counties for a given item.  As long as one of the selection criteria has
only one value, the description of that value will appear on screen displays and
printouts as a second-level heading.  Thus, you need only one set of labels to
describe the data.

Selecting records

Because of the structure of the data files, selecting data items, like the
number of acres of wheat harvested, is a matter of selecting records (not
selecting "items", as with economic census files).  This process is made more
difficult because item codes in both the county files and the state files are
unrelated to any coding scheme with which users may already be familiar (such as
SIC codes or commodity codes).

The best aid to finding the data items you want is to find them first in one of
the 1987 Census of Agriculture geographic area series reports, then note their
table number and relative position within the table.  The first two digits of
each item code in state and county files are the table number.  (Otherwise the
item codes in state and county files are unrelated.)

    Record selection in county files.  For the county files, selecting records
is aided by a menu of all items available.  The <J>ump function allows you to
specify a particular table number, e.g., 18, whereupon the menu will jump to all
items with a 5-digit code beginning with 18.  From that point you browse through
as many screens as are necessary to find, and select with X's, all of the items
you want.  Note that there is a maximum of 17 items that can be checked off at
any one time.  If you need more, you will need to revert to selection in terms
of a range of codes.

If you don't know the table number, the <W>ord search and <L>ocate options can
come in handy.  <W>ord search prompts for any string of characters, and, after a
few minutes, the system will present you with a list of all of the labels in
which that string of characters appears.  The system will find the desired

                                                 36
string of characters anywhere on a line, upper or lower case, but it may also
pick up that string as part of another word.  For example, searching for Apples
will also bring up lines for Pineapples.  Select with X each of the codes you
want.

Somewhat faster in operation is the <L>ocate option, which will also accept a
string of characters, but will look for them only at the beginning of a line. 
<L>ocate is faster than <W>ord search because <L>ocate stops looking once it has
found the first occurrence and displays the full list starting at that point.

In any record selection which involves either the item number or the county
code, the record selection process will automatically use that state's index
file to find the first eligible record.  That index is sequenced item code by
county, so that, until that index is turned off, all displays will be sequenced
item by county; for example, the count of farms would be shown for all counties,
then land area in acres for all counties, and average acres per farm for all
counties.  If you want those three items together for each county, you can type
"N" for natural sequence when the data are displayed to screen sorted by item,
or you can turn off the index before going in to the data display screen, as
discussed below.

Selecting multiple items for multiple (or all) counties can take a great deal of
time.  The preferred way to query the file in EXTRACT is either to select a
single item to display for multiple counties, or to select multiple items to
display for a single county (turning off the index before displaying).  If you
want to display a number of counties for two or three items or a number of items
for two or three counties, it is much faster to structure them as two or three
separate queries, perhaps printing out the results for future reference, than to
do it all at once.

To turn off the item-by-county index prior to data display, select Manipulate
Files (option 4) from the main menu, then Select an Existing Index (option 1)
from the Manipulate Files menu, and finally press <ESC> to escape from the index
selection screen.

    Record selection in the state file.  For the state file, selecting records
is made more awkward because there is no separate reference list of data items
that can be brought up for record selection.  Thus, selecting based on the
ITEM_ST code can be done only by specifying a range.  To look at all codes
corresponding to table 18, enter 18 as the minimum value and 19 as the maximum
value.  Once you have displayed the data to the screen and scrolled through the
many records to find the data you want, make note of the applicable ITEM_ST
codes for future reference.

Another factor affecting the selection of data from the state file is the fact
that each data item is defined by not one but two 60-character labels.  In
general, TEXT1 defines the row stub in the corresponding printed table while
TEXT2 defines what would have been the column header.  There are two ways to see
both sets of labels at once.

    Switch to rowwise display, which will show only one record at a time but
    will give both full 60-character labels.

    Use the "W" option in the normal columnar display to specify a narrower
    column <W>idth.  Simply highlight any value in the column to be narrowed,
    type "W", and the system will prompt for the number of characters of the
    column to display.  By truncating the text1 and text2 fields to fewer than

                                                 37
    34 characters each, both can be displayed on the screen at the same time
    along with at least one data value.  Note that if you really need to see the
    last part of a text field you have truncated, merely highlight the desired
    entry and press "S" for <S>how.  That will display the entire text across
    subsequent lines, until you move the cursor.


U.S. Exports and Imports of Merchandise

The CD-ROMs in these two monthly series do not include EXTRACT-compatible
auxiliary files, which must instead be obtained in compressed form on Economic
Census CD-ROMs 2B or 1E, on diskette from the Center for Electronic Data
Analysis (see address under Getting Assistance, above).  Two levels of
installation are available, a compact installation occupying 130 kb on your hard
disk, and a preferred installation, with somewhat more legible and useful
commodity menus, requiring 3.4 megabytes more.

While the master catalog includes both export and import data, no one CD-ROM has
both, and you must insert the appropriate disc for the query you make.

Each import and export database already includes text labels, or at least
mnemonics, for the commodity, country, and district, as applicable.  The "add
labels" function is still useful, particularly in attaching alternate codes to
each commodity.  (SIC, SITC, End Use and Agriculture codes are available as
labels.)

Each disk contains summary files of moderate size, and an enormous detailed data
set of 200 to 500 megabytes.  Each database is indexed, but data retrievals from
the largest data sets can be fairly time consuming.  Record selection involving
a single value (e.g., imports from Iraq or exports of a particular commodity)
can be accomplished reasonably quickly.  Record selection based on widely
separated codes (e.g., imports from Venezuela (code 3070) and Nigeria (code
7530) can be extraordinarily time consuming (hours!), but if the requests are
made separately, one code value at a time, they can be accomplished in a few
minutes.


County Business Patterns

The 1986-87 and 1987-88 CD-ROMs do not include EXTRACT-compatible auxiliary
files, and the 1988-89 CD-ROM is missing one critical auxiliary file. 
Fortunately, the 1988-89 CD includes auxiliary files in compressed form
(\EXTRACT\CBPAUXIL.EXE) which, once installed on a hard disk (about 930 kb), can
service all three of the CDs issued as of this writing.  (A substitute master
catalog for the 1988-89 disk can be obtained from the BBS which requires less
hard disk space if earlier CDs are not being used.)  

Narrative definitions are available for key data items, but descriptive informa-
tion for SIC categories are limited to the 56-character title.  Note that the
SICs recognized for the 1986 and 1987 CBP are on the 1972/77 basis.  About 1/4
of all SICs were redefined for the 1987 Economic Censuses.  The 1988 and 1989
CBP data are reported on the new basis, consistent with the 1987 Economic
Censuses.





                                                 38
County and City Data Book, 1988

EXTRACT-compatible auxiliary files may be obtained in compressed form on
Economic Census CD-ROMs 2b or 1e, on the Census Bureau electronic bulletin
board, or on a diskette from the Center for Electronic Data Analysis.  When
installed on your hard disk, the auxiliary files require about 635 kilobytes.

Each file in this data set includes data for all states, all counties or all
cities nationwide, but only a limited number of items are included in each file. 
Thus, for example, age statistics might be in one file while race statistics are
in another.  This is quite unlike the structure of economic and agriculture
census files which more often segment the data by state rather than by subject
matter.  

Within the places file PLF01, the system cannot successfully select records
based on county (the STCO variable), due to a quirk in index structure.  It is,
however, possible to select on state code.


USA Counties, 1992

EXTRACT-compatible auxiliary files may be obtained in compressed form from the
census Bureau electronic bulletin board, or on a diskette from the Center for
Electronic Data Analysis.  When installed on your hard disk, the auxiliary files
require about 1.1 megabytes.  Due to certain conventions unique to the USA
Counties disc, EXTRACT 1.4a (November 1992) or later is required to work with
this CD-ROM.

Each file in the data set includes data for all states and counties nationwide. 
The 2080 statistics and their flags are segmented across 35 separate files, and
you may wish to consult the master list of data items in the documentation or in
the file CO_DDF.dbf (in the AUXIL catalog) to determine which items are in which
files.  The Add Labels function is an easy way to link into a single display
items from two or three files.  The COSTATPF.dbf data base consolidates 51 of
the most frequently used items into a single source, and, in fact, is the only
file that contains the 1990 census population count.

The variables most often used for record selection are ST, to select the state
total and all counties in a state; METRO, to select all counties in a metro area
(there are not MSA summaries); and SUMLEV, to select all state totals.  When
selecting a specific county or group of counties, select on both STate and
COUnty.  Initially the county menu will start with Alabama counties, even if
another state has been selected, but you may <J>ump to the appropriate state if
you recall the appropriate state code from the previous step.  You may select up
to 14 individual counties at this point, but they must all be in the same state. 
If you need counties from multiple states, select all counties within those
states with the ST code.


1990 Census CD-ROMs:  STFs 1A, 1B, 1C, 3A, 3B, and 3C; PL94-171; EEO Files 

Earlier versions of the auxiliary files that EXTRACT needs to work with STF 1A,
STF 1B, and PL94-171 discs were included in compressed form on Economic Census
CD-ROM 2b.  Revised versions reducing hard disk requirements somewhat, as well
as auxiliary files for STF 1C and STF 3A, may be downloaded from the Census
bulletin board, or may be purchased on diskette from the Institute for
Electronic Data Analysis at the University of Tennessee.  One compressed file

                                                 39
STFAUX.EXE (309k) contains a set of auxiliary files needed for all of these CDs,
supplemented by other files needed in addition to service particular 1990 census
CDs [STFAUX1A.EXE (61k), STFAUX1B.EXE (11k), STFAUX1C.EXE (50k), STFAUX3A.EXE
(225k), and PL94AUX3.EXE (12k) are available at this writing].  When
uncompressed, auxiliary files for all of these CDs require about 3.1 megabytes
of hard disk space.  Auxiliary files unique to STF 3B, STF 3C, and the EEO files
will be issued later in 1992.

While EXTRACT 1.2 and 1.3 worked with the original auxiliary files for STF 1A,
STF 1B, and PL94-171, EXTRACT 1.4 or later is required to deal with the new ver-
sion of the auxiliary files designed to save hard disk space.  (The new approach
saves more than 1.1 megabytes in an installation including STFs 1A and 3A.)

Comparison of EXTRACT and GO

If you simply want to look up numbers, one area at a time, the GO software
distributed on each of the 1990 census CD-ROMs is much easier and more efficient
than EXTRACT.  The program prompts you to pick a summary level, then a specific
area, and finally a particular table.  One of the tables is a "general profile"
presenting 89 key items selected or derived from the 982 population and housing
data fields carried in the 10 STF 1A databases.  If you want to see the more
detailed data, you may look at any one table at a time.  That table, or the
general profile, may be printed to your printer or to a file, one area at a
time.

Because this GO software was created specifically to work with the STF 1A discs,
it insulates the user from much of the complexity of the STF 1A files--data
stored in multiple files, with cryptic variable names, and with complex geo-
graphic hierarchies.  As such, GO is highly appropriate for novice users.

EXTRACT, on the other hand, requires you to deal with more of the complexity of
the data set, but gives you much more power and flexibility in working with the
data, including the following capabilities:

    -       To deal effectively with classes of geographic areas, such as all
            places within a county or all tracts with 1 or more person of
            Hispanic origin.
    -       To work with data from more than one table at a time.
    -       To view narrative concept definitions so you understand what you are
            working with.
    -       To create "user-defined items", such as population per square mile,
            percent white, or a count of persons under 15.
    -       To merge these data with data from other sources, such as the
            economic censuses.
    -       To copy to a file whatever subset of data you select, so that you
            can import the data into other applications, such as Lotus 1-2-3(tm)
            or Harvard Graphics(tm).
    -       To work these data using a tool you have learned how to use with
            other Census Bureau data sets.

Dealing with the 10 STF 1 files and 34 STF 3 files

Since there are over a thousand geographic, population and housing fields in STF
1, and no dBase file can contain more than 128 fields, STF 1A and STF 1C are
structured as a series of ten parallel files for each State.  Even larger, STF 3
files consist of 34 parallel files.  When working with STF 1A, EXTRACT prompts


                                                 40
you to select one of the ten as your starting point in the "Select a Catalog"
screen:
 
File    Matrixes        Subjects covered 
 
STF1A0  P1 - P10        Geographic Identifiers, Sex, Race, Hispanic Origin 
STF1A1  P11 - P12(p2)   Age, Total and White 
STF1A2  P12(p3-p5)      Age, Black and American Indian, Eskimo, Aleut (male) 
STF1A3  P12(p6-p8)      Age, American Indian .(female) and Asian or Pacific 
STF1A4  P12(p9)-P13(p1) Age, Other Race and Hispanic Origin (male) 
STF1A5  P13(p2) - P19   Age, Hispanic Origin (female), Household Rel. & Type 
STF1A6  P20 - P35       Household Relationship & Type (cont.), Imputations 
STF1A7  P36, H1 - H20   Housing: Vacancy, Tenure, Age of Hhr, Rooms, Persons 
STF1A8  H21 - H40       Persons Per Room, Value, Rent, Duration of Vacancy 
STF1A9  H41 - H55       Units in Structure, Housing Imputations

Since this is rather limited as a subject locator, you will want to keep handy a
copy of the subject locator (pages 3-1 to 3-6) or the table outlines (pages 5-1
to 5-11) in the printed STF 1 or STF 3 CD-ROM documentation, or to print out the
corresponding ASCII text files SUB_LOC.ASC and TBL_OUT.ASC in the \DOCUMENT
subdirectory of the CD-ROM.

If you expect to return to the file selection menu several times during a
particular session, it will be worthwhile to type R to <R>estrict the session to
data for a particular state before selecting the catalog.

You can combine into your display data from one or two more of these subject
areas using "Add Labels" discussed below.

Displaying data to the screen

From the main menu, which you reach after specifying drives and selecting the
file you want, your first step is likely to be option 6--Display to screen.  If
you selected STF1A0 or STF300, you are confronted with columns of codes and no
data.  The data are there, but you must cursor to the right past more than 60
codes to find them.  Thus, it is helpful to select only certain columns to
display, which is accomplished through option 1--Select Items--at the main menu.

Selecting items

When using a STF1A0 file, the Select Items menu extends through 11 screens (move
down with <PgDn>).  The first four screens are all codes, mostly in alphabetic,
not logical or hierarchical order.  Area name (ANPSADPI) appears on the fifth
screen, 10 lines before the first of the population statistics.  The first of
the subject items, P0010001, is on the sixth screen.  The <J>ump feature allows
you to enter "ANPSADPI" or "P001" to jump right to particular items if you know
their mnemonics.

After selecting items it is generally useful to type P to <P>review how the data
will appear in columns across the screen.  Initially, the area name (ANPSADPI)
takes up 66 characters, leaving room for only one or two other items on the
screen.  Cursor to the right until you get to that column, then press W for
<W>idth, and specify a narrower column, e.g. 12 characters. 

Selecting records



                                                 41
SUMLEV or summary level is the most important of the geographic codes for record
selection on all of the 1990 census CD-ROMs, since it identifies the type of
geography.  To select records for all counties, for example, select SUMLEV and
the value "050--Counties" on the summary level menu--even though your first
inclination might be to select based on CNTY, the county code.  The CNTY
variable comes into play in selecting data for a single county.  To display all
tracts or BNAs within a particular county, select on both SUMLEV and CNTY (put 2
S's on the first menu) and specify a SUMLEV of "140" for TRACT's and BNA's.  

Understanding summary levels and the sequencing of records is so important that
you will want to keep handy the summary level sequence chart on page 6-1 of the
STF 1 or STF 3 documentation (or print out the first part of
\DOCUMENT\SUM_LEV.ASC on the CD-ROM).  You also need to keep straight which
codes are available on which summary levels.  For example, if you want to
analyze tracts/BNAs by place, you need to specify a SUMLEV of "080" instead of
"140", because SUMLEV 140 tract/BNA records do not include place codes, while
SUMLEV 080 tract/BNA records do not.  Similarly, if you want to list places
within a county, you need to work with SUMLEV 155, not SUMLEV 160, because the
latter do not have county codes.  To determine which codes are available on
which summary levels, see STF 1 documentation pages 2-3 to 2-15 or print out
\DOCUMENT\HOWTOUSE.ASC.

The best variables for selecting records are highlighted on the first record
selection screen with an asterisk (*)--these codes can be selected from a menu
and also have indexes to speed your search.  Of these, SUMLEV, CNTY (county),
and PLACEFP (place) are easiest to use.  COUSUBFP (county subdivision) and
TRACTBNA (census tracts/BNAs) lists are sequenced by county, so it is advisable
to select records in two stages--first, using only CNTY, and then again from the
main menu with COUSUBFP or TRACTBNA.

Any variable in the data set can be used as a selection variable, including
population (e.g., all block groups with 1 or more Hispanic residents) or even
latitude and longitude.  Unfortunately, since the files are so large (from 8 to
286 megabytes per state), and it can take 5 minutes per megabyte for scanning
through unindexed records on a CD-ROM, it is advisable to make such selections
only within a particular county, place, or tract/BNA.

Adding labels

For STFs 1A and 3A, the area name field (ANPSADPI) appears only on the first
file in each series (STF1A0 or STF300).  When working with other files, you may
add labels associated with the county, county subdivision, place, or the lowest-
level name (ANPSADPI).  To add ANPSADPI, use the Add Labels options at the main
menu, and select "--STF1A0" or "--STF300" at the first Add Labels menu, and
ANPSADPI at the second menu.  (This is not an issue for STF 1B, STF 1C, or PL94-
171 CDs, where all files contain ANPSADPI.)  

The Add Labels feature can be used to link data items from other files on the
same CD-ROM as well as area names.  At the second Add Labels menu, you may type
A to select from <A>ll data items, not just labels, and M to select <M>ultiple
items from that screen.  For example, you could select not only the area name
from STF1A0, but also the total population (P0010001).  Labels can be specified
from up to two sources, allowing you to view data from as many as three files at
once.  Adding labels does, however, slow down data display.

Displaying definitions


                                                 42
One of EXTRACT's unique features is its ability to display definitions of
geographic and subject concepts.  Typing D at the Select Items menu or in the
columnar display screen will bring up a concept <D>efinition keyed to the
variable currently highlighted.  You may also explore the definitions of related
variables by typing I to bring up an <I>ndex of all of the topics for which
narrative discussions are available.  A table locator for STF 1A and a 3-part
table locator for STF 3 are also available from the this index.  You also may
access definitions from the main menu (type D <enter>).

Notes particular to P.L. 94-171 CD-ROMs

Most data displays for subcounty areas should include the voting district
identifier entitled "Special Area Code 3" (SAC3), since voting districts split
many place, tract/BNA, and block group summaries, and govern their sequence in
any case.

When selecting records, the speediest access to data is provided by selecting on
SUMLEV, PLACECE, CNTY, or CNTY and SAC3 together; and by specifying only one
code at a time within the second-level record selection menus.

Note that some codes are not available at all on the P.L. 94-171 files (noted in
the menus) and others are available only within certain record types (see Figure
2 in the P.L. 94-171 documentation).


GETTING ASSISTANCE                           EXTRACT Help Lines: (301) 457-4151
                                                                       457-1210

This program was designed to promote the effective use of data on Census Bureau
CD-ROMs.  If, after reading this documentation, you have questions about the
operation of the program, or have found what appears to you to be an error or
"bug" in the program or documentation, you may call Paul Zeisset or Bob Marske
of the Census Bureau's Economic Planning Staff at (301) 457-4151.  Written
correspondence may be directed to the Economic Planning Staff, Bureau of the
Census, Washington, D.C.  20233.  

If you think you have encountered a program bug, first see if you can reproduce
the problem.  If you call the help line, you may need to be able to tell the
person at the other end of the line the precise sequence of steps that brought
you to the problem.  If the program has terminated abruptly, i.e., "bombed",
then EXTRACT leaves a 1-line message at the top of the screen that may be the
key to determining the problem.  Write the message down precisely (or send it to
your printer with <shift><Print Screen>).  If you access EXTRACT through a
menuing system that takes you back to the menu without giving you time to record
any error message, try to run EXTRACT outside the menuing system (i.e., from a
C> prompt) or have your menu designer insert a "pause" command after running
EXTRACT.  That way you can record any error message before calling for help.

Among the most common problems that cause program termination is insufficient
random access memory (usually a "run error").  EXTRACT requires about 450 kb of
RAM, and network drivers or terminate-and-stay-resident programs may have to be
removed while you are using EXTRACT.  Another problem (usually indicated by a
message citing an ".NDX" file) results from the use of EXTRACT under an extra
memory manager like QEMM(tm).  Type "SET CLIPPER=E000" before running EXTRACT if
you encounter that problem.  An error message starting "Proc ADDLABVALU"
generally indicates that you have attempted to extract a file with a user-
defined item not wide enough to accommodate the largest value.


                                                 43
It helps to be at your computer when you call the EXTRACT help line.

    Electronic Bulletin Board System (BBS).  You may view the latest bulletins
on EXTRACT use, read comments other users have made, and also leave your own
questions, comments, or suggestions to other users on data retrieval strategies
on the Census Bureau electronic bulletin board under the "CD-ROM" conference. 
The latest version of EXTRACT and auxiliary files for particular CD-ROMs are
available for downloading without charge on the BBS.  That board may be reached
on (301) 457-2310 (computer).  The first time you call, you are asked to
complete an on-line registration form.  (For voice assistance in logging into
the bulletin board, call (301) 457-1242.)
                                       
In addition to the above mentioned sources, EXTRACT and auxiliary files are
included on both 1987 and 1992 Economic Census CD-ROMs.






































                                                 44

                        INDEX TO EXTRACT DOCUMENTATION


1987 Economic Census CD-ROMs        35    Economic census CD-ROMs             35
1990 Census CD-ROMs                 39    Editing 
                                            an extracted data file            33
Aborting EXTRACT with <alt>C        34      your MY_FILES catalog             23
Adding labels                       15    EEO files                           39
  1990 census CD-ROMs               42    Electronic bulletin board           43
  Agriculture census CD             36    Error messages                      43
Advanced Options                    23      Run error                          2
Advanced topics                     24    Exports and Imports CD-ROMs         38
Agriculture census CD-ROMs          36    EXTRACT menu, setting up            25
Auxiliary files                           EXTRACT.PRM                         24
  defined                           24    Extracting data to a file           21
  for 1990 census STF CD-ROMs       39
                                          File manipulation                   26
Bulletin board for software updates 43    File selection menu
                                            first time through                 5
Catalog files, description          24      second time through               23
Catalog selection                    5    Footnote files 
Color, problems with display         8      in census of manufactures         35
Column width                        20    Foreign trade CD-ROMs               38
Columnar display                    18    Format Options                      17
  Selecting from Format Options     17
Comma-delimited extract files       21    GO software                         39
Command-line parameters             25
Config.sys                           2    Headings                            17
Counting number of records selected       Headings, 2nd level              14,17
  ("Dry Run")                       22    Help screen files                   24
County Business Patterns CD-ROMs    38    Help screens                         6
County and City Data Book CD-ROM    39    Help via electronic bulletin board  43
Cursor movement--to top or                Help via telephone                  43
  bottom of file                    19    Horizontal file merging             28

Data dictionary functions           24    Indexes
Data dictionary, creating a new one 34      creating a new index              27
DBF extract files                   21      selecting an existing index       27
Definition display                        Installation
  from data display screen          19      of EXTRACT                         2
  from main menu                     7      of auxiliary files
  from Select Items                  9        --see "____READ.ME" files
  from Select Records               12    Institute for Electronic Data 
  on 1990 census CD-ROMs            42      Analysis, Univ. of Tennessee      43
Deleting records
  from an extract file              33    Jump to a particular...
  from your MY_FILES catalog        23      code--Select Records              12
Diskettes with EXTRACT software             field name--Select Items           9
  and auxiliary files               43      field name--Add Labels            16
Display to screen                   18
Drive specification                  4
Dry run to estimate file size       22





                                                 45
Label files                               Saving format options               23
  functions                         24    Saving parameters                 4,25
  looking without linking           33    SDF extract files                   21
Labels                              15    Secondary files display             33
  from more than one file           16    Select Items                         8
  illustration                      19      on 1990 census CD-ROMs            41
  multiple labels from one file     16    Select Records                      10
Locate a particular description             on 1990 census CD-ROMs            41
  Add Labels                        16      on agriculture census CD          36
  Select Items                       9      reinstating previous criteria     14
  Select Records                    12      with conditional clauses          32
Lotus 1-2-3                          1    Sequence of items in display        30
  importing data into 1-2-3         21    Showing 
                                            full contents of truncated column 19
Main menu                            7      record selection criteria          8
Manipulate files                    26    Sorting (creating a new index)      27
Margins--printed output             17    Speed of execution                  18
Marking a record                    19    Speed-up-retrieval prompt           13
Master catalog                       4    STFs 1A, 1B, 1C, 3A, 3B, and 3C     39
  functions                         24    Storage requirements 
  as needed for 1988-89 CBP CD-ROM  38      of extract files                  22
Menus, setting up your own to             SUMLEV                           13,41
  access different CD-ROMs          25
Merging files                       28    Toggling between columnar and 
MicroSoft Extensions                 2      rowwise display                   20
MY_FILES catalog                          Totals 
  accessing extracted files         23      across multiple records           31
  adding to it                      33      of items in the same record        9
  editing                           23    Tutorials                            1
  new entries                       22
MY_FILES.cti catalog of indexes     28    USA Counties CD-ROM                 39
                                          User-defined items                   9
PL94-171                         39,42
Page length--printed output         17    Vertical file merging               30
Percents and similar computations    9
Previewing columnar display          9    Width of column                     20
Printer settings                           in Preview mode                     9
  changing fonts with software      21    Word search
  margins, headings                 17      in Add Labels                     16
Printing                            21      in Select Items                    9
  to a file                         22      in Select Records                 12
PRN extract files                   21    Work directory
                                            creation                           2
RAM requirements                     2      as default location for 
Ranges, selecting a range of codes  12        extracted files                 22
Ranking                             27
Record selection                    10
  economic census CDs               35
  reinstating previous criteria     14
  showing criteria in effect         8
  strategies                        12
RECTYPE                             13
Restricting session to files for 
  a State                            5
Rowwise display                     20
  selecting from Format Options     17
Run error                         2,43

                                                 46