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PUBLICATIONS NATT. INST 0F STANDARDS & TECH R.I.C. NBSIR 86-3471 „ All 10263 1548

D/The internal Revenue Serv QC100 .U56 NO.86-3471 1987 VI 9 C.1 NBS-P The Internal Revenue Service

Post-Of-Duty Location Modeling

System - User’s Manual

Paul D. Dom;ch, Richard H. F. Jackson, Marjorie A. McClain

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Applied Mathematics

Gaithersburg, MD 20899

July 1986

Issued February 1987

Cnnnrnrgd by;

-Q0 esearch Division

100 3l Revenue Service

.1)56 ngton, DC 20224

86-3471

1987

NBSIR 86-3471

THE INTERNAL REVENUE SERVICE

POST-OF-DUTY LOCATION MODELING

SYSTEM - USER’S MANUAL

NBS

RESEARCH

INFORMATION CENTER /Vi^SR

(Xcfoo

YXO, 26.

IH7

Paul D. Domich, Richard H. F. Jackson, Marjorie A. McClain

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Applied Mathematics

Gaithersburg, MD 20899

July 1986

Issued February 1987

Sponsored by:

The Research Division

Internal Revenue Service

Washington, DC 20224

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Director

ABSTRACT

This report is a user's guide for a microcomputer package which was

designed by the National Bureau of Standards to assist the Internal Revenue

Service in choosing locations for its posts-of -duty which will minimize

costs to the IRS and to the taxpayer. The user may select the types of

costs to be considered and may specify potential locations for new posts-ofduty. The system displays maps showing workload for a district, current

post-of-duty locations and new post-of-duty locations. This manual

provides hardware and software requirements for the system, installation

procedures, data file formats, and detailed operating instructions.

Keywords: facility location, interactive graphics, greedy heuristic,

interchange heuristic, personal computer, microcomputer,

Graphical Kernel System, zip code map

TABLE OF CONTENTS

Section I: Introduction . 1 A. Description of Reports 1 B. Introduction to the System 2

Section II : Computer Requirements 4

A. Hardware . 4

B. Software 4

Section III: Setting Up the System 5 A. Graphics Device Drivers, AUTOEXEC.BAT and

CONFIG.SYS Files 5 B. Program Files 6 C . Data Files 6

Section IV: Using the System 11

A. Overview 11

B. Entering the System 15

C. Exiting from the System • . 17

D. Displaying Workload 18

E. Displaying or Modifying Initial POD Sites 22

F. Solving for Optimal POD Locations 27

G. Displaying Optimal POD Locations 30

Index 34

Section I: Introduction

A. Description of Reports

This paper is one of a series of reports documenting the Internal

Revenue Service Post-of-Duty Location Modeling System, which was developed

for the IRS Research Division by the Center for Applied Mathematics of the

National Bureau of Standards. The reports in the series are as follows.

1)

The Internal Revenue Service Post-of-Dutv Location Modeling System:

Final Report

This report describes the post-of-duty location problem and its

mathematical model. It discusses the types of data which are considered

in calculating costs, describes the methods used to solve the location

problem, and gives a brief introduction to the computer implementation of

the model. (NBS Contact: Richard H. F. Jackson)

2)

The Internal Revenue Service Post-of-Dutv Location Modeling System:

User's Manual

This report is a user's guide for the post-of-duty location computer

system. It gives hardware and software requirements, instructions for

installing the system, descriptions of data files, and detailed

instructions for operating the system. (NBS Contact: Marjorie A.

McClain)

3)

The Internal Revenue Service Post-of-Dutv Location Modeling System:

Programmer's Manual for FORTRAN Driver

The post-of-duty location program is written in two sections of code, one in FORTRAN and the other in PASCAL. This report describes the FORTRAN

driver which handles graphics displays and controls input and output for

the solution procedure. The report includes an alphabetical list of the

FORTRAN routines, describing the purpose, the calling sequence and the

variables of each routine. (NBS Contact: Marjorie A. McClain)

4)

The Internal Revenue Service Post-of-Dutv Location Modeling System:

Programmer's Manual for PASCAL Solver

This report describes the second part of the post-of-duty location

program, the PASCAL solver. It discusses the algorithms and data

structures used to solve a location problem. (NBS Contact: Paul D. Domich)

1
B . Introduction to the System

The Internal Revenue Service Post-of-Duty Location System is a microcomputer package designed to assist IRS district planners in choosing

locations for posts-of-duty (POD's) which will minimize costs to the IRS and

to the taxpayer. The package uses color graphics in performing the

following functions.

1) Displaying Workload

The user may choose the type of workload to be displayed, such as the number of returns examined or the number of criminal investigation cases. Then a state zip code map is drawn, with each zip

code shaded according to ’ the workload it generates

.

2) Displaying Initial POD Sites

A state zip code map is drawn showing where POD's are currently

located and also where new POD's could potentially be located. The

user may make modifications to this information to specify POD's

which may not be or must be in the set of POD's determined by the

solution procedure.

3) Solving for Optimal POD Locations

Using the initial POD information specified by the user, the

solution procedure calculates the cost of assigning each zip code to

each current or potential POD. The cost includes travel costs

associated with the workload of each zip code, office rental costs,

and costs of opening new POD's or closing old POD's. The user may

set parameters indicating what types of workload (such as taxpayer

service or criminal investigation) should be included in the travel

cost calculations. Also, weights may be assigned to pairs of zip

codes and POD sites to scale travel costs. The user must specify

the number of POD's desired in the solution. The solution procedure

then determines the set of POD's which will result in the least

total cost for the district.

4) Displaying Optimal POD Locations

A state zip code map is drawn showing where the new POD's determined

by the solution procedure are located. Also, a report file is

generated which summarizes the problem specification and the

solution. The report includes a list of which zip codes are to be

assigned to which POD's.

5) Controlling Display of Maps

On any of the state zip code maps mentioned above, the user may zoom

in on a small region, back up to a larger region, or find the fivedigit zip code number of an area on the map.

2
This manual describes how to set up and use the POD location system.

Section II contains the computer hardware and software requirements.

Section III explains the procedure for installing the system and describes

the format of required data files. Section IV contains detailed

instructions on how to operate the system.

Note: Reference to a tradename or product in this report does not imply

endorsement by the National Bureau of Standards.

3
Section II: Computer Requirements

A. Hardware

The POD location system has been designed to run on an IBM-PC XT or AT

equipped with a math coprocessor and with one of the following types of

displays

1) IBM Enhanced Graphics Adapter with Enhanced Color Display

This display has a screen size of 640x350 pixels and uses 16 colors.

Text, lines and marker symbols are drawn in high resolution, and

shaded regions of maps are filled using solid colors. The system

requires at least 128KB of graphics memory, rather than the standard

64KB. This extra graphics memory is necessary in order to display

16 distinct colors; without enough memory, colors which are different in the graphics program may look the same on the screen

(so, for example, a shaded map may appear to be all one color).

2) IBM Color Graphics Monitor Adapter

This display, used in medium resolution mode, has a screen size of

320x200 pixels and uses four colors. Text characters are larger

than on the enhanced display, so menus take up a greater proportion

of the display screen. Shaded regions of maps are filled using

cross-hatching

A printer is desirable, but not necessary.

The system may also run on IBM-compatible machines, but due to the use of graphics device drivers (see Section III Part A) for the specific

displays listed above, unpredictable results may occur if other displays are used. The system has been successfully tested on a Compaq Deskpro with a Princeton Graphics Quadchrome monitor and on a Compaq portable. It may be

possible to use a PC with no fixed disk, but the package was not designed

for this

B . Software

To run the POD location system, the following software is required.

1) IBM-PC DOS (Version 2 . 1 or later)

2) IBM Virtual Device Interface (VDI) and device drivers

3) Executable code for the POD location system

A programmer who wants to be able to make changes in the system will need

additional software, such as source code, IBM Professional FORTRAN, Turbo

PASCAL, and the IBM Graphical Kernel System. See "The Internal Revenue

Service Post-of-Duty Location Modeling System: Programmer's Manual for

FORTRAN Driver" and "The Internal Revenue Service Post-of-Duty Location

Modeling System: Programmer's Manual for PASCAL Solver" for further

information.

4
Section III: Setting Up the System

This section describes how to install the system for the first time or when updates need to be made to data files. It is assumed that the user who

initially sets up the system is thoroughly familiar with IBM- PC DOS and, in

particular, can work with subdirectories and create and make changes in data

files using a text editor. However, once the system has been properly

installed, detailed knowledge of DOS is not necessary to use it.

A. Graphics Device Drivers. AUTOEXEC.BAT and CONFIG.SYS Files

The graphics portion of the POD location program was written using a subroutine library called the Graphical Kernel System (GKS) . Running a program which uses GKS requires the presence of the Virtual Device Interface

(VDI) , which links the program to the type of graphics display device being

used. The VDI files INIT_VDI.EXE, VDI . SYS and either VDIDY010.SYS (for an enhanced color display) or VDIDY004.SYS (for a regular color display) must

be copied into the root directory or a subdirectory.

Next, the VDI must be initialized in the CONFIG.SYS file and optionally

in the AUTOEXEC.BAT file. These files contain commands which are executed

by the computer as soon as it is turned on. They must be in the root

directory and may be created or modified using a text editor. The files

should contain the following statements

.

AUTOEXEC . BAT

\path\INIT_VDI

CONFIG . SYS

FILES-10

BUFFERS—10

DEVICE—\path\ANSI . SYS

DEVICE-\path\VDIDY010 . SYS (for an enhanced color display)

DEVICE-\path\VDIDY004 . SYS (for a regular color display)

DEVICE—\path\VDI . SYS

Notes

:

1) \path\ indicates the full DOS path name giving the location of the file.

It is needed only if the file is not in the root directory.

2) After making any changes to the AUTOEXEC.BAT or CONFIG.SYS files, the

computer must be restarted for the changes to take effect.

3) ANSI. SYS is a file provided with DOS; INIT_VDI.EXE, VDIDY010 . SYS

,

VDIDY004 . SYS and VDI . SYS come with the VDI.

5
4) VDI.SYS must be the last device listed in the CONFIG.SYS file.

5) An enhanced color display can be made to appear like a regular color

display by using the VDIDY004.SYS device driver. Both device drivers can be listed in the CONFIG.SYS file; the last one listed will be the default

display mode used by an application program. To switch to the other

device driver, type "SET DISPLAY=\path\VDIDYXXX. SYS" (where "XXX" is

either "004" or "010") before running the program.

6) The DOS "shift-printscreen" command for making printed copies of a display screen will only work with the VDIDY004 device driver. It does

not copy enhanced graphics screens. (Type GRAPHICS before running a program in which printed copies of graphics screens are desired; see the

DOS manual for more information.)

7) FILES=10 and BUFFERS=10 are values suggested by the Professional FORTRAN

manual for use with Professional FORTRAN programs.

8) If the device driver has not been properly initialized, the message

"CANNOT OPEN WORKSTATION" will appear when trying to run an application

program.

9) It is not actually necessary to include INIT_VDI in the AUTOEXEC.BAT

file. It may be executed any time before running an application program.

B . Program Files

A directory should be created on the fixed disk to contain the POD

location system programs and data files. Copy the following program files

from the floppy disk provided to the new directory.

1) TEMPZIP . BAS

2) UNFORM . EXE

3) SAVCEN.EXE

4) TEMPSTE . BAS

5) BINSTE.EXE

6) LOCATE . BAT

7) DRIVER . EXE

8) SOLVER.COM

The first five programs listed are used only once, for initializing data

files (see Part C) . The last three are used to run the POD location system,

where the batch file LOCATE controls the execution of DRIVER and SOLVER.

(For more information on these programs, see Section IV.)

C . Data Files

The data files required by the POD location system can be divided into

two categories: (1) geographic data files used to draw maps and (2) IRS

data files used to initialize and solve a location problem. The data files

contain information on a state-wide basis, even if the IRS district of

interest is only part of a state. For a given state, each data file is

6
named using the state code number followed by a three-letter extension

indicating the type of data in the file. The state code number may be

determined by looking at the name of the provided zip code boundary file.

For example, STATE12.ZIP is the name of the file containing zip code

boundary coordinates for Florida. In the following description, "XX" is

substituted for the state code number.

1) Geographic Data Files

The system is currently designed using zip code boundary data from

Ganesa 's Statmap package. This data must be processed before it can be

used by the POD location system. (The initialization process only

needs to be done once, when the system is first installed. After that,

it is done only when updates are made to the zip code files.)

Procedure

a) Switch to the POD location system directory and type BASICA TEMPZIP.

Enter the state code number when the program prompts for it, and also

the number of floppy disks containing the Ganesa zip code boundary

file STATEXX.ZIP. Then the program will give instructions to insert

each floppy disk in the A: drive. The terminal will beep after each

disk is read, which may take several minutes apiece. After all the

disks have been read, the message "ZIP CODE FILE LOADED" will appear

on the screen. Type SYSTEM to exit from BASIC. A new file called

STATEXX.TMP will exist on the fixed disk, which contains the zip code

boundary file with end- of -record marks added.

b) Type UNFORM and enter the state code number when prompted. This

program will run for several minutes to create a new file called

STATEXX.ZIP, which is an unformatted direct access version of

STATEXX.TMP. This is done to increase the speed of file accessing.

STATEXX.TMP should be deleted after UNFORM has been run to save disk

space, since the system uses only the unformatted version.

c) Type SAVCEN and enter the state code number when prompted. This

program calculates the centroid of each zip code in STATEXX.ZIP. It

creates a new file called STATEXX.CEN, which is an unformatted direct

access file containing five-digit zip codes, centroids, and pointers

to the boundary file.

d) Type BASICA TEMPSTE and enter the state code number when prompted.

Insert the floppy disk containing the Ganesa state boundary file

STATEXX.ST into the A: drive. The program will create a new file

called STATEXX.TM on the fixed disk, which contains the state boundary

file with end-of -record marks added. Exit from BASIC by typing SYSTEM.

e) Type BINSTE and enter the state code number when prompted. This

program creates a new file called STATEXX.STE which is an unformatted

direct access version of STATEXX.TM. STATEXX.TM should be deleted

after BINSTE has been run, since the system uses only the unformatted

version.

7
Note: The Ganesa coordinate files will eventually be replaced by GDT

files, so the above procedure will be changed and probably simplified.

There will be an additional procedure for setting up a zip code adjacency

file to be used with the map-coloring algorithm. Also, provision will be

made for districts which are not entire states.

2) IRS Data Files

Two files of IRS data are required which contain current POD information

and workload data for a given state. The names of these files are STATEXX.POD and STATEXX.WRK. If these files are provided by the National

Office on a floppy disk, they should be copied into the POD location

system directory. (Another file, STATEXX.GDF, may also be provided. If

so, copy it too.) Otherwise, the files must be created using a text

editor. The format of the files is as follows.

a) STATEXX.POD:

The purpose of this file is to maintain a list of the zip codes and

associated costs of all POD sites which currently exist in the state

and also of potential new POD sites. The first line of the file

should contain the total number of possible POD sites (current and

potential) for the state, followed by the office space requirement

(given as square feet per IMF return) . Each remaining line (one line

per POD site) should contain the five-digit zip code of the site, the

opening or closing cost for a POD at the site ($), and the rental cost

for office space at the site ($ per square foot per month) . Current

POD sites should have minus signs in front of their zip codes. (This

determines whether the second number is an opening or closing cost;

current POD sites have closing costs and potential POD sites have

opening costs.) Numbers in the file should be separated by spaces,

and the zip codes should be listed in sequential order.

Example

:

9 .062

-20001 1.0 3.0

-20003 .5 .5

20004 2.0 1.5

20007 1.5 1.0

-20010 2.0 2.0

-20013 2.0 1.0

20014 1.5 .5

-20015 2.0 2.5

-20018 1.0 2.0

This example shows nine POD sites, six of which are current POD sites

b) STATEXX.WRK:

The first line of this file should contain the travel cost ($ per

mile) and the travel distance limit (miles) for the state. (The

travel distance limit is the maximum distance that a person would be

expected to travel to reach a POD site.) The second line should

8
contain the 16 IRS trip factors, one for each category of workload

(see below) . (An IRS trip factor is the average number of trips an

IRS employee must make for each case in a particular category.)

Similarly, the third line contains the 16 taxpayer trip factors (the

average number of trips a taxpayer must make per case) . Each

remaining line of the file (one line per zip code, listed in

sequential order) should contain a five-digit zip code followed by 16

numbers giving the workload for that zip code in each of the following

categories

1) Examination - Class 1

2) Examination - Class 2

3) Examination - Class 3

4) Examination - Class 4

5) Examination - Class 5 6) Examination - Class 6

7) Examination - Class 7 8) Examination - Class 8

9) Examination - Class 9

10) Examination - Class 10

ID Examination - Class 11

12) Examination - Class 12

13) Collection - TDI's

14) Collection - TDA's

15) Taxpayer Service

16) Criminal Investigation

Example

.205

1. 0.

800

0 0. 0. 0 0. 0. 0. 0. 0. 0. 0. 0

1. 0. 0 0. 0. 0 0. 0. 0, 0. 0. 0, 0. 0

20001 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20002 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20003 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20004 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20005 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20006 6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20007 7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20008 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20009 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20010 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20011 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20012 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20013 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20014 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20015 6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20016 7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20017 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

20018 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

0 . 0.

This example shows a state with eighteen zip codes , with nonzero

workload in only the first category. (The numbers are given only to

9
show the format of the workload file and are not intended to represent

realistic data.)

To summarize , the following data files must exist to run the POD location

system.

1) STATEXX.ZIP (zip code boundary file)

2) STATEXX. CEN (centroid file)

3) STATEXX . STE (state boundary file)

4) STATEXX. POD (POD file)

5) STATEXX. WRK (workload file)

These files are set up when the system is first installed and only need to

be changed when updates are made to the data.

10
Section IV: Using the System

A. Overview

This introduction gives a general overview of the steps a user should

go through to solve a location problem. Detailed instructions for each step

are provided in later parts of this section. The overview also describes

how maps are used in the system and explains how to use the cursor to locate

zip codes and to zoom in on maps.

Steps in Solving a Location Problem

(Before the system is used for the first time, several data files must be

set up. See Section III for information on how to do this.)

1) Enter the system.

Type LOCATE to enter the system, and identify the state to work on. Wait

for the top-level menu to appear. (See Part B for more information on entering the system.)

2) Display workload.

This step may be repeated at any time, or it may be skipped. Select the

function for displaying workload- from the top menu. Choose the category

of workload to be displayed. A state map will appear which can be zoomed

in on to show zip codes shaded according to their workloads. (See Part D

for more information on displaying workload.)

3) Display and initialize POD information.

Return to the top menu and select the function for displaying and

modifying initial POD sites. A state map will appear with asterisks

showing where POD's are currently located. Zoom in on the map to an area

of interest, and then color in zip codes to indicate whether they are to

be considered as currently existing POD sites, potential new POD sites,

or fixed POD sites which cannot be moved. Zip codes which are not

colored cannot be POD sites. (See Part E for more information on

displaying POD information.)

4) Initialize cost information and solve for best POD locations.

Return to the top menu and select the function for solving for optimal

POD locations. Set options as requested to select categories of workload

to be considered in the cost calculation and to choose weights for IRS

and taxpayer costs. Travel difficulty factors may be entered for pairs

of zip codes and POD sites which are separated by geographic barriers.

Choose the number of POD's desired in the solution. The solution

procedure will then begin, and a summary of the stages of the process

will appear on the screen. (See Part F for more information on initializing and solving a location problem.)

11
5) Display solution.

Select the function for displaying optimal POD locations from the top menu. A state map will appear with asterisks showing where POD's have

been placed by the solution procedure. Zoom in on the map to areas of

interest. (See Part G for more information on displaying a solution.)

6) Exit from the system.

Return to the top menu and select the function for exiting from the

system. Examine the report file, which summarizes the location problem

and its solution. (See Part C for more information on exiting from the

system.

)

Use of Mans

In several of the steps listed above, maps are drawn to display

information. Although the type of information is different at each step,

the procedure for manipulating the maps is the same. The user may zoom in on a small region, back up to a previous map, or find the five-digit zip

code number of an area on the map.

The first map drawn always shows the outline of the state and centroids

of certain zip codes, but no zip code boundaries. (The reason for not

including zip code boundaries at this level is that many of them are too

small to be distinguished and it would take a very long time to draw them

for the whole state.) A menu appears to the left of the map giving the user several choices on how to proceed.

1) Exit

This option returns the user to the top menu.

2 ) Zoom

This option allows the user to zoom in on the map to display zip code

boundaries in a small region. When this option is chosen, instructions

appear in the menu area telling how to use the cursor to draw a box

around the area to be enlarged. First a crosshair ( + ) cursor appears in

the center of the screen, which can be moved using the arrow keys and the

"home", "end", "page up" and "page down" keys on the right side of the

keyboard. Move the cursor to one corner of the area to be enlarged; then

press return («-J ) to enter the coordinates of this point into the

computer. (The cursor normally moves in large increments. To make it

move in smaller increments, first press the "insert" key.) Next, move

the cursor to locate the opposite corner of the box. This time the box

is actually drawn on the screen. Then press return to enter this point.

The old map will be erased from the screen, and a new map showing zip

codes in the boxed area will be drawn. A new menu will appear on the

left side (see below) . If a mistake was made in entering the box

corners (for example, if both comers were the same point), the message

"TRY AGAIN" will appear; start over, again entering both corners of the

12
box. The user may take advantage of this feature to cancel an undesired

box, by entering an intentional mistake for the second corner.

3

)

Full Display

This option causes the full state map to be drawn with zip code

boundaries included. It is expected that this option will normally not

be used. A new menu will appear on the left side of the screen (see

below)

After either of the last two options above is chosen, a new menu

appears on the left side of the screen with the following options.

1) Exit

This option returns the user to the top menu.

2 ) Zoom

This option allows the user to zoom in on a specified area of the current

map. The procedure for drawing a box around the area is the same as given above. After the new map has been drawn, the same menu of options

appears. The user may zoom as many times as desired.

3 ) Back Up

This option redraws the previous map and its display menu. Only one level of backing up is allowed. For example, if five zooms had been

done, only the fourth map could be redisplayed. However, it is always

possible to return to the full state map and then zoom in again.

4) Full State

This option redraws the full state map showing the state boundary and zip

code centroids.

5 ) Map Key

This option displays a key which defines what the colors on the map mean. Two further options are available at this level. First, the user may

exit from the map key and return to the menu of display options. Second,

the user may move the cursor to locate a zip code on the map and have its

five -digit number displayed in the lower left corner of the screen.

The cursor is moved with the arrow keys and the "home", "end", "page up"

and "page down" keys on the right side of the keyboard. Pressing the

"insert" key makes the cursor move in small increments. To locate a zip

code, move the cursor near the centroid of the zip code and press return «—*) . The five-digit zip code number will be written at the bottom of

the menu area. If the cursor is too far away from a centroid, the

message "ZIP NOT FOUND" will be written instead.

13
It is important that the cursor be positioned close to the centroid of

the zip code region of interest. The program that prints the five -digit

zip code does not recognize the boundaries on the map, so it is not

necessarily enough merely to have the cursor in the correct region. The

zip code printed is that of the nearest centroid to the cursor, whether

it is in the same region as the cursor or not.

In addition to the two options discussed above, other options are available on the POD initialization map for changing the colors of zip

codes. See Part E for information on how to do this.

The remainder of this report provides descriptions of menus and

detailed instructions for each step used in solving a POD location problem.

14
B . Entering the System

To enter the POD location system, switch to the directory containing

the system files (using the DOS "Change Directory" command) and type LOCATE.

Enter the state code number when prompted. (This number is provided with

the system data files when the package is installed.

)

If a report file exists from a previous session, the system will then

ask whether the report is to be overwritten. (See Part C for information on

the report file.) If the user answers "yes", the old report file will be

replaced by a new report on the current session. If the user answers "no",

the new report will be appended to the old report file.

The message "SORTING CENTROIDS" will then appear, followed by a brief

pause. (If the pause lasts for more than a minute or if the message "CANNOT

OPEN WORKSTATION" appears , check for device driver errors in the

AUTOEXEC.BAT or CONFIG.SYS files. See Section III Part A.) Then the toplevel menu will appear on the screen, as shown in Figure 1.

IRS POSTLOCATION

-OF-DUTV

S VST EM

FI - Exi t

F2 - Display workl oad . F3 - Display

i n i t i a 3. op Modify

POD sites.

F4 ~ Solve for opt i Mia 1 POD locations.

F5 - Display op t i Mai

POD locations.

Figure 1. Top-level menu.

This menu lists the steps used to solve a POD location problem, along with a function key number for each step. To make a selection from the menu, just

push the corresponding function key (no return ^—I is necessary) . The

following is a brief description of each of the choices in the top menu. For a more complete description, see the subsection listed in parentheses.

15
FI - Exit (Part C)

Exits from the POD location system.

F2 - Display workload (Part D)

Draws a map showing workload for each zip code.

F3 - Display or modify initial POD sites (Part E)

Draws a map showing where POD's are currently located and also where

new POD's are allowed to go. The user may alter this information by

coloring the map, and the data is saved for use by the solution

algorithm (see F4)

.

F4 - Solve for optimal POD locations (Part F)

Solves the location problem initialized using F3

.

F5 - Display optimal POD locations (Part G)

Draws a map showing the new POD locations determined using F4.

16
C . Exiting from the System

To exit from the POD location system, choose FI from the top menu. The system will automatically delete several work files which were created

during the session. For reference, the names of these files are NAMES,

ERRORS. GKS, STATEXX. DBL and STATEXX.SOL.

After exiting from the system, the user should examine the report file

STATEXX. REP, either by scanning it with a text editor or by listing it on a printer. This file contains a summary of all parameters used to set up a location problem and a list of POD's and zip code assignments in the

solution, if these steps were performed during the session. (Reports of

previous sessions may also be contained in the same file.)

17
D . Displaying Workload

The F2 function in the top menu is used to display a map showing

workload for each zip code. Before drawing the map, the system will ask the

user to choose the category of workload to be displayed from the following

list

.

1) Examination (Number of returns in classes 1-12)

2) Collection (Number of TDI's and TDA's)

3) Taxpayer Service (Number of notices)

4) Criminal Investigation (Number of cases)

5) Single Column of Workload File

Type the number of the desired category. If category 5 is selected, the

user will be prompted to type in the number of the column to be displayed (a

number from 1 to 16) . (See Section III Part C for a description of the

workload columns.) The workloads are then read in from the file STATEXX.WRK

and are divided into six equally spaced ranges. A color is assigned to each

zip code based on which range its workload lies in. This information is not

displayed immediately, but is stored for later use.

While the file is being read, the system compares the zip codes in the

workload file with the zip codes in the boundary file which will be used to

draw the map. If any zip codes appear in the workload file but not in the

boundary file, they will be ignored. If any zip codes appear in the

boundary file but not in the workload file, they will be drawn as blank

areas on the workload map. In either case, a message will appear on the

screen indicating which zip codes were mismatches so that the user may check

if the workload file is accurate.

After the workload file has been read and colors have been calculated,

a map showing only the state boundary and small boxes for zip code centroids

is drawn. No zip code boundaries are drawn at this level. On an enhanced

graphics display, the centroids are drawn in six different colors, with

brighter colors indicating higher workloads. On a regular color display,

all the centroids are drawn in yellow; the user must zoom in on the map in

order to see the workload. To the left of the state map, a menu of display

options appears on the screen (see Figure 2)

.

18
DISPLAY

OPTIONS

FlEXIT

F2-

200M

F3-FULL

DISPLAY

Figure 2. Full state map display menu.

The menu choices are discussed below,

FI - Exit

Exits from the workload display mode and returns to the top menu.

F2 - Zoom

Zooms in on a specified area of the map to display workload there. See

Part A for a complete description of how to use the cursor to draw a box around the area. A new map showing zip code boundaries in the

boxed area will be drawn, and a mew menu will appear (see below).

F3 - Full Display

Draws a map of the full state showing zip code boundaries and

workloads. It is expected that this option will normally not be used,

since the zip codes will be too small and the map will take a long time

to draw. A new menu will appear on the left side of the screen.

After choosing F2 or F3 from the full state display menu, the menu of

display options shown in Figure 3 will appear.

19
DISPLAY

OPTIONS

FiEXIT

F2-

200M

F3-

BACK UP

F4-FULL

STATE

F5~

MAP KEY

Figure 3. Zip code map display menu.

The options are described below.

FI - Exit

Exits from the workload display mode and returns to the top menu.

F2 - Zoom

Zooms in on a specified area of the current map. See Part A for a complete description of how to use the cursor to draw a box around the area. After the new map has been drawn, the same menu of display

options appears. The user may zoom as many times as desired.

F3 - Back Up

Redraws the previous map and its display menu. Only one level of

backing up is allowed.

F4 - Full State

Redraws the full state map showing the state boundary and zip code

centroids. The full state display menu also reappears.

F5 - Map Key

Displays the map key shown in Figure 4 defining what the zip code

colors mean.

20
WORK

LOAD

FI -EXIT

F2-FIND

SIPCODE

min EES3

EH

USE

F1-F2

Figure 4. Workload key.

There is a color for each of the six possible workload ranges, listed

in order from the lowest workload to the highest workload. Two menu

options exist.

FI - Exits from the workload key and returns to the menu of display

options

F2 - Allows the user to locate a zip code on the map using the cursor

and have its five -digit number displayed in the lower left corner

of the screen. (The procedure for using the cursor to locate a zip code is described in Part A.)

21
E . Displaying or Modifying Initial POD Sites

The F3 function in the top menu is used to display a map showing

current POD sites and other potential POD sites. This information is read

from the file STATEXX.POD. The user is allowed to make modifications by

changing the colors on the map. The modified POD information is saved for use later by the solution algorithm.

Before the map is drawn, the system checks to see that all POD zip

codes appear in the master list of zip codes obtained from the boundary

file. If any mismatches occur, a message will appear on the screen and the

POD will be ignored by the system. The user should check on the accuracy of

the file STATEXX.POD.

After the zip codes have been checked, a map showing only the state

boundary and centroids of certain zip codes is drawn. On an enhanced

graphics display, centroids of current POD sites are drawn as red asterisks

and centroids of other potential POD sites are drawn as small blue boxes;

other zip code centroids are not drawn. On a regular color display,

centroids of current POD sites are drawn as red asterisks; centroids of all

other zip codes are drawn as yellow boxes. A menu of display options

appears on the left side of the screen (see Figure 5)

.

22
DISPLAY

OPTIONS

FlEXIT

F2-

300M

F3-FULL

DISPLAY

Figure 5. Full state map display menu.

The menu choices are discussed below.

FI - Exit

Exits from the POD initialization mode and returns to the top menu. The current POD set-up is saved to be used later by the solution

algorithm. If F3 is entered again from the top menu, the previous

set-up is erased and a new initialization is begun.

F2 - Zoom

Zooms in on a specified area of the map to display POD information

there. See Part A for a complete description of how to use the cursor

to draw a box around the area. A new map showing zip code boundaries

in the boxed area will be drawn, and a new menu will appear (see

below)

F3 - Full Display

Draws a map of the full state showing zip code boundaries and POD

information. It is expected that this option will normally not be

used, since the zip codes will be too small and the map will take a long time to draw. A new menu will appear on the left side of the screen.

After choosing F2 or F3 from the full state display menu, the menu of

display options shown in Figure 6 will appear.

I 23
DISPLAV

OPT I ONS

FIEXIT

F2-

SOOM

F3-

BACK UP

F4- FULL

STATE

F5-

IMIAP KEY

Figure 6. Zip code map display menu.

The options are described below.

FI - Exit

Exits from the POD initialization mode and returns to the top menu. The current POD set-up is saved to be used later by the solution

algorithm. If F3 is entered again from the top menu, the previous

set-up is erased and a new initialization is begun.

F2 - Zoom

Zooms in on a specified area of the current map. See Part A for a complete description of how to use the cursor to draw a box around the area. The same menu will appear after the new map is drawn, and the

user may zoom as many times as desired.

F3 - Back Up

Redraws the previous map and its display menu. Only one level of

backing up is allowed.

F4 - Full State

Redraws the full state map showing the state boundary and zip code

centroids. The full state display menu also reappears.

F5 - Map Key

Displays the map key shown in Figure 7 defining what the zip code

colors mean.

24
POD

tvpes

Fl-EXIT

F2-FXMB

3IPC0DE

F3-SET

COLOR

F4- CZj

CANT BE

F5- WZ

MAV BE

USE

F1-F2

Figure 7 . POD map key

A function key is associated with each color to allow colors to be

changed on the map. The functions are as follows.

FI - Exits from the map key and returns to the menu of display options.

F2 - Allows the user to locate a zip code on the map using the cursor

and have its five -digit number displayed in the lower left corner

of the screen. (The procedure for using the cursor to locate a zip code is described in Part A.)

F3 - Enters the mode for changing the color of a zip code on the map.

The zip code must have been located already using F2

F4 - Sets a zip code to be a site which is not allowed to have a POD.

The coloring mode must have been entered using F3

F5 - Sets a zip code to be a site which is allowed to have a POD but

does not currently have one. The coloring mode must have been

entered using F3

F6 - Sets a zip code to be a site which currently has a POD. The

coloring mode must have been entered using F3 . Current POD sites

are allowed to be removed by the solution algorithm.

F7 - Sets a zip code to be a site which must have a POD. The coloring

mode must have been entered using F3 . Sites which must have a POD are fixed and will not be removed by the solution algorithm.

To summarize, the map originally shows current POD sites and other

potential POD sites as read from the file STATEXX.POD. The user may

25
fix a POD site or make other changes by first locating the zip code

(F2) , entering the coloring mode (F3)

,

and then choosing the correct

color (F4, F5 , F6 or F7)

.

A message is always given at the bottom of

the menu area telling which functions keys can currently be used; if

any other key is pushed it will be ignored.

26
F. Solving for Optimal POD Locations

The F4 function in the top menu is used to solve a POD location problem

given an initial configuration of current, potential and fixed POD sites, as set up using the F3 function. F3 creates data structures which must be used

by F4, so F3 must always be done first even if no modifications are to be

made to the configuration read from the input file.

After F4 is pushed, the system will allow the user to set various

parameters to be used in calculating costs. The following list of default

parameter settings will appear on the screen.

# ITEM POSSIBLE ACTUAL

1 IMF EXAMINATION 0,1 | 1

2 IMF COLLECTION 0,1 | 1

3 IMF TAXPAYER SERVICE 0,1 | 1 4 IMF CRIMINAL INVESTIGATION 0,1 | 1

5 BMF EXAMINATION 0,1 1 0

6 BMF COLLECTION 0,1 | 0

7 BMF TAXPAYER SERVICE o,i 1 0

8 BMF CRIMINAL INVESTIGATION o,i | 0

9 TAXPAYER TRAVEL COST WEIGHT [0. 0-1.0] | 1.00000000

10 IRS TRAVEL COST WEIGHT [0. 0-1.0] | 1.00000000

11 MAXIMUM TRAVEL DISTANCE IN MILES | 80.00000000

The first eight items indicate which categories of workload should be

included in the cost calculation; a value of 1 means the category is

included and a value of 0 means it is not included. (In the current version

of the system, Business Master File (BMF) data cannot be included.) The

next two items are weights to be assigned to IRS employee travel costs and

taxpayer travel costs. For example, setting the IRS weight to 0 and the

taxpayer weight to 1 would cause the solution procedure to consider only

costs to the taxpayer. The weights can have any decimal value from 0 to 1,

and they need not add up to one. The final item on the parameter list is

the maximum distance that a person would be expected to travel between a zip

code and a POD. The value listed (in this example, 80 miles) is read from

the file STATEXX.WRK. The distance limit is used to cut down on storage

space and on the running time of the solution procedure, since zip codes

separated by too large a distance can be eliminated from consideration.

The system then asks whether the user wishes to change any of the

default parameter settings. If the answer is "yes", the user is asked to

enter the number of the item to be changed and its new value. These should

be typed on one line, separated by a space. The new value will then appear

in the parameter list, and the user may proceed to make further changes.

Next, the system will ask if the user wants to change any travel

difficulty factors. These are weights which are assigned to pairs of zip

codes and POD's to scale their travel costs. This is especially useful in cases where, for example, a zip code and a POD site are close together but

are separated by some geographic barrier which makes travel between them

difficult. By assigning a high weight to the pair, the user makes it

unlikely that the solution procedure will try to assign the zip code and POD

to each other. It should be kept in mind that the solution procedure

27
automatically takes distances between zip codes and POD's into account when

making assignments, so distance should not be considered when setting

difficulty factors.

Default settings for travel difficulty factors are read from the file

STATEXX.GDF if it exists; otherwise all factors are assumed to be equal to one. If the user responds "yes" to the question on changing travel

difficulty factors, new values may be entered into the file. Type a zip

code, a POD zip code and the new factor on one line separated by spaces.

The factor may be any positive number. A factor greater than one implies

that travel is of more than average difficulty; a factor less than one implies easier travel.

After all options have been set, there will be a pause for several

minutes while the workload file STATEXX.WRK is read and all possible zip

code pairs and their costs are computed. (For a complete mathematical

description of the cost calculation, see "The Internal Revenue Service Postof-Duty Location Modeling System: Final Report".) The zip codes in the

workload file are compared with the master list of zip codes obtained from

the boundary file. If any zip codes appear in one file but not the other,

they are eliminated from consideration by the solution procedure. A message

will be printed on the screen whenever a skip occurs, but the solution will

proceed normally based on the subset of zip codes which appear in both

files. The user may wish to modify the workload file to correct the skips

(see Section III Part C)

.

It is possible that for some zip code there may be no POD site within

the required distance limit. In this case, the message "INITIAL POD SITES

NOT FEASIBLE" will appear on the screen. The user should then either

increase the distance limit or set more potential POD sites.

After costs for each zip code pair have been calculated, a summary is

printed giving the total number of zip codes, the total number of possible

POD sites (current and potential) , and the number of currently existing

POD's. Then the user is prompted to enter the number of POD's desired in

the solution. This can be any number from one to the total number of

possible POD sites.

The solution algorithm then begins and passes through four phases .

1) Initial Assignment

Zip codes are assigned to the currently existing POD's, and the total

cost of the assignment is printed on the screen.

2) Initial Interchange

Each current POD is examined to see if it can be switched with another

potential site to give a lower allocation cost. A message is printed on the screen whenever a switch is made. The result at the end of this

phase is a better arrangement of the initial set of POD's. The cost of

the new arrangement is printed on the screen.

28
3) Greedy Heuristic

In this phase, POD's are added to (or deleted from) the initial set until

the specified number of POD's has been reached. One POD is added (or

deleted) at a time, and it is chosen as the site which, when taken with

the initial set, will give the lowest possible allocation cost. Messages

are printed on the screen telling which POD's have been added (or

deleted) and what the allocation cost is at each step.

At some stage of the solution algorithm, a message may appear saying that

a solution is infeasible. This means that for some zip code it was impossible to find a POD site within the specified maximum distance

limit. The algorithm will proceed using the last known feasible number

of POD's for the final interchange.

4) Final Interchange

In the last phase, the set of POD's determined by the greedy heuristic is

examined to see if any POD in the set should be switched with one not in

the set. The switches are listed on the screen along with the final

allocation cost.

The solution is stored for later display, and the top menu reappears on

the screen.

29
G . Displaying Optimal POD Locations

The F5 function in the top menu is used to display a map showing the

solution to the POD location problem determined using the F4 function.

Also, information on the solution, including assignments of zip codes to

POD's, is written in the report file STATEXX.REP (see Part C) . First a map

of the state boundary is drawn, with asterisks indicating the centroids of

POD's in the solution. The menu of display options shown in Figure 8

appears on the left side of the screen.

30
DISPLAY

OPTIONS

FlEXIT

F2-

ZOOM

F3-FULL

DISPLAY

Figure 8. Full state map display menu.

The menu choices are discussed below.

FI - Exit

Exits from the solution display mode and returns to the top menu.

F2 - Zoom

Zooms in on a specified area of the map to display the solution there

See Part A for a complete description of how to use the cursor to draw

a box around the area. A new map showing zip code boundaries in the

boxed area will be drawn, and a new menu will appear (see below)

F3 - Full Display

Draws a map of the full state showing zip code boundaries and POD

locations. It is expected that this option will probably never be

used, since the zip codes are too small and the map will take a long

time to draw. A new menu will appear on the left side of the screen.

After choosing F2 or F3 from the full state display menu, the menu of

display options shown in Figure 9 will appear.

31
Figure 9. Zip code map display menu.

The options are described below.

FI - Exit

Exits from the solution display mode and returns to the top menu.

F2 - Zoom

Zooms in on a specified area of the current map. See Part A for a complete description of how to use the cursor to draw a box around the area. The same menu will appear after the new map is drawn, and the

user may zoom as many times as desired.

F3 - Back Up

Redraws the previous map and its display menu. Only one level of

backing up is allowed.

F4 - Full State

Redraws the full state map showing the state boundary and zip code

centroids. The full state display menu also reappears.

F5 - Map Key

Displays the map key shown in Figure 10.

32
NEW

PODS

FI - EX I

F2-FIND

2IFC0DE

* = POD

USE

F1-F2

Figure 10. Solution map key.

Only the zip codes which the solution algorithm determined should be

POD sites are colored on the map and their centroids are shown as asterisks. The following options exist on the menu.

FI - Exits from the solution key and returns to the menu of display

options

F2 - Allows the user to locate a zip code on the map using the cursor

and have its five-digit number printed in the lower left corner of

the screen. (The procedure for using the cursor to locate a zip

code is described in Part A.)

Note: It is planned that, in a future revision of the POD location system,

the solution map will be able to show assignments of zip codes to POD's,

rather than just showing POD sites. A POD and all its assigned zip codes

will be drawn in the same color.

33
INDEX

A

Adjacency file 7-8

ANSI. SYS 5 AUTOEXEC.BAT 5-6, 15

B

Back up (to previous map) 13, 20, 24, 32

BINSTE.EXE 6, 7 Boundary file 7, 10, 18, 22, 28

BUFFERS statement 5, 6

C

Centroid 7, 10, 12, 13-14, 15, 18, 20, 22,

Closing costs 2, 8

Color graphics monitor adapter 4, 5-6, 18

CONFIG.SYS 5-6, 15

Coprocessor 4

Cost options 11, 27-28

Current POD sites 2, 8, 11, 16, 22, 25, 27, 28

Cursor 12, 13-14

D

Data files 6-10

Device driver 4, 5-6, 15

DEVICE statement 5-6

Distance limit 8, 27, 28

DOS 4,5

DRIVER . EXE 1, 6

E

Enhanced color display 4, 5-6, 18

Enhanced graphics adapter 4

ERRORS. GKS 17

Exiting from the system 12, 16, 17

F

File name format 6-7

FILES statement 5, 6

Final interchange 29

Find zip code with cursor 13-14, 21, 25, 33

Fixed POD sites 2, 11, 25-26, 27

FORTRAN 1, 4, 6

Full display of a state zip code map 13, 19, 23, 31

Full state map display menu 12-13, 19, 23, 31

Function keys , use of 15

G

Ganesa 7

GDT 7 Geographic data files 7 GKS 4,5

Greedy heuristic 29

34
Graphical Kernel System 4, 5

H

Hardware requirements 4

IInfeasible solution 28, 29

INIT_VDI .EXE 5,6

Initial assignment 28

Initial interchange 28

Interchange heuristic 28, 29

IRS data files 8-9

»L

LOCATE . BAT 6, 11, 15

M

Map key,

POD types 25

solution 33

workload 21‘ Map options 12-14

Math coprocessor 4

Memory requirements 4

Mileage cost 8

N

NAMES file 17

0

Office rental costs 2, 8

Office space requirement 8

Opening costs 2, 8

Optimal POD display 2, 12, 16, 30-33

P

PASCAL 1 , 4

POD file 8, 10, 22

POD map key 25

POD site display 2, 11, 16, 22-26

POD site modification 2, 11, 16, 22-26

POD site types 11, 25

Potential POD sites 2, 8, 11, 16, 22, 25, 27, 28

Previous map 12, 13, 20, 24, 32

Printer 4, 6, 17

Program files 6

R

Rental costs 2, 8 Report file 2, 12, 15, 17, 30

Resolution of screen 4

35
sSAVCEN.EXE 6, 7

2, 11, 22, 27-28

Screen resolution 4

Set color 11, 14, 16, 25-26

SET DISPLAY statement 6

Setting up a POD location problem

Software requirements 4

SOLVER.COM 2, 6

Solving a POD location problem 1, 2, 11, 16, 27-29

Solution algorithm 1, 28-29

Solution display 2, 12, 16, 30-33

Solution map key 33

State boundary file 7, 10

State boundary map 12, 13

STATEXX. CEN 7, 10

17

28

10 , 30

18, 20, 22, 24, 30, 32

8 , 8 , 17,

17

22, 25

STATEXX. DBL

STATEXX. GDF

STATEXX. POD

STATEXX. REP

STATEXX. SOL

STATEXX. ST

STATEXX. STE

STATEXX. TM

STATEXX. TMP

STATEXX. WRK

STATEXX.ZIP

Statmap 7

Switching device drivers

7, 10

8-9, 10,

7, 10

18, 28

I

TEMPSTE . BAS 6, 7 TEMPZIP .BAS 6,7

Top menu 11, 15-16

Travel costs 2, 27

Travel difficulty factors 11, 27-28

Travel distance limit 8, 27, 28

Trip factors 8-9

U

UNFORM . EXE 6, 7

V

VDI 4, 5-6

VDI .SYS 5,6

VDIDY004 .SYS 5,6

VDIDY010 .SYS 5,6

Virtual Device Interface 4, 5-6

W

Work files 17

Workload categories 9, 18, 27

Workload file 8-9, 10, 18, 27, 28

Workload display 2, 11, 16, 18-21

Workload key 21

Workstation error 15

36
zZip code boundary file 7, 10, 18, 22, 28

Zip code map display menu 13-14, 20, 24, 32

Zoom 2, 12-13, 19, 20, 23, 24, 31, 32

37
NBS-H4A i rev. 2 -ac) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 86-3471

2. Performing Organ. Report No. 3. Publication Date

FEBRUARY 1987

4. TITLE ANO SUBTITLE

The Internal Revenue Service Post-of-Duty Location Modeling System - User's Manual

5. AUTHOR(S)

Paul D. Domich, Richard H. F. Jackson, Marjorie A. McClain

6. PERFORMING ORGANIZATION (If joint or ocher than NBS, see in struction s) national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

The Research Division

U. S. Internal Revenue Service

1201 E Street

Washington, DC 20224

10.

SUPPLEMENTARY NOTES

I Document describes a computer program: SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bi bl iography or literature survey, mention it here)

This report is a user's guide for a microcomputer package which was designed by

the National Bureau of Standards to assist the Internal Revenue Service in choosing

locations for its posts-of-duty which will minimize costs to the IRS and to the

taxpayer. The .user may select the types of costs to be considered and may specify

potential locations for new posts-of-duty. The system displays maps showing

workload for a district, current post-of-duty locations and new post-of-duty

locations. This manual provides hardware and software requirements for the system,

12. installation procedures, data file formats, and detailed operating instructions.

KEY WORDS (Six to twelve entries; alphaoeti cal order; capitalize only proper names; and separate <ey -vorCs ay semicolon •.

i facility location, interactive graphics, greedy heuristic, interchange heuristic,

personal computer, microcomputer, Graphical Kernel System, zip code map

13. AVAILABILITY 14. NO. OF

PRINTED PAGES

| X| Unlimited

[

j For Official Distribution. Do Not Release to NTIS

1

1 Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

42

15. Price

! y | Order From National Technical Information Service (NTIS). Springfield, VA. 22161 $ 11.95

jSCOmm.OC