
                                   1:100,000-Scale
                              Digital Line Graph (DLG)
                         Hydrography and Transportation Data
                                      on CD-ROM

        This CD-ROM was produced in accordance with the ISO 9660 standard.
        The CD-ROM contains hydrography and transportation DLG data for
        the Hawaiian Islands (Section 14) in the optional distribution
        format.  The data format is the same as that used for distributing
        the data on 9-track magnetic tape.  However, carriage returns and 
        line feeds (HEX 0D and 0A) have been added to each 80 bytes.  This 
        was done to create physical records which are more compatible with 
        DOS and UNIX-based applications.  The NOCRLF program located in the
        DLGSOFT subdirectory has been provided for users who need to remove 
        the carriage returns and line feeds.

        A menu program is provided to assist Disk Operating System (DOS)
        users in accessing the information files and the program (EXTRACT)
        for copying the data from the CD-ROM to the user's system.  To get
        started, make the CD-ROM drive the current drive by typing the
        drive letter and a colon.  Then type DLG followed by a <RETURN> at
        the DOS prompt.

        The menu program and the EXTRACT software currently run only in
        the DOS environment.  There are no plans for other platforms.
        Non-DOS users will need to provide software that reads one or more
        of the data formats mentioned above.  The C source code for
        EXTRACT is provided in the \SOURCE subdirectory and programmer's
        documentation (EXTRACT.DOC) is provided in the \DOCFILES
        subdirectory.


                                     DISCLAIMER

        This Compact Disc Read Only Memory (CD-ROM) was prepared by an
        agency of the U.S. Government.  Neither the U.S. Government nor
        any agency thereof, nor any of their employees, make any warranty,
        expressed or implied, or assume any legal liability or
        responsibility for the accuracy, completeness, or usefulness of
        any information, apparatus, product, or process disclosed in this
        report or represent that its use would not infringe privately
        owned rights.  Reference therein to any specific commercial
        product, process, or service by trade name, trademark,
        manufacturer, or otherwise does not necessarily constitute or
        imply its endorsement, recommendation, or favoring by the U.S.
        Government or any agency thereof.  Any views and opinions of
        authors expressed herein do not necessarily state or reflect those
        of the U.S. Government or any agency thereof.

        Although all data and software published on this CD-ROM have been
        used by the USGS, no warranty, expressed or implied, is made by
        the USGS as to the accuracy of the data and related materials and
        (or) the functioning of the software.  The act of distribution
        does not constitute any such warranty, and no responsibility is
        assumed by the USGS in the use of this data, software, or related
        materials.


                                SYSTEM REQUIREMENTS

        An IBM or compatible personal computer equipped with a CD-ROM
        drive and an EGA/VGA graphic display are required to use the
        1:100,000-scale DLG CD-ROM.  It is recommended that 80286-, 80386-,
        or 80486-based machines be used.  The CD-ROM will run with an
        8088-based PC, but a significant increase in processing time will
        occur.  At least 512 Kbytes of available random access memory
        (RAM) is required and Microsoft CD-ROM extensions (version 2.01 or
        higher) must be installed.  A mouse is not required, but the
        software will take advantage of one if present.  This CD-ROM was
        produced according to the ISO 9660 standard.

        NON-DOS USERS

        The EXTRACT software runs in a DOS environment only, and there are
        no plans for other platforms.  However, the files on the CD-ROM
        may be accessed from other platforms due to conformance with the
        ISO 9660 standard for the production of the CD-ROM.  The C source
        code for the EXTRACT program is located in the SOURCE subdirectory.


                               CD-ROM DIRECTORY STRUCTURE

        The subdirectory structure and a description of the files follows.

                                      Root Directory

                                         README.1ST
                                         DLG.BAT
                                         INSTALL.EXE
                                              |
                     ___________________________________________________
                      |           |           |           |
                      \DOCFILES   \SOURCE     \DLGSOFT    \100K_DLG



        README.1ST  - General information file similar to what you are
                      currently reading.

        DLG.BAT     - The command to start the menu program.

        INSTALL.EXE - Program to install the software onto your hard
                      disk.

           \DOCFILES -    Subdirectory containing the text files used by the 
                          menu program, the EXTRACT program documentation, 
                          and the DLG Data Users Guide 2.  The user guide 
                          gives information about the DLG data files and is 
                          provided in both Word Perfect 5.1 and ASCII text 
                          formats.  The user guide files are as follows:

                          dug2.txt    - 80 column ASCII format (portrait pages
                                        only)
                          dug2.wp     - WP 5.1 format (portrait pages only)
                          dug2tab.txt - Landscape Appendix pages; ASCII format
                          dug2tab.wp  - Landscape Appendix pages; WP 5.1
                                        format

           \SOURCE -      Subdirectory containing the source code files
                          for:

                          EXTRACT program - Selects layers and area to be
                          transferred to a hard disk.

                          FILEBROW program - Allows you to view an ASCII
                          text file.

                          INSTALL program - Installs the software onto your
                          hard disk.

                          100KUTIL program - Contains various functions used
                          by the program that may be used in other programs
                          by linking the source code with 100KUTIL.

                          NOCRLF program - Removes carriage returns and line 
                          feeds.  Written in QuickBASIC.

                          FONT file - Include file that contains the text
                          fonts used in graphics mode.

                          MESSAGE file - Include file that contains the lines
                          of text that are displayed on the screen.

           \DLGSOFT -     Subdirectory containing the executable programs
                          EXTRACT (including graphic files), PKUNZIP,
                          FILEBROW, and NOCRLF.
                                         
           \100K_DLG -    The data files for each 1:100,000-scale
                          quadrangle are in individual subdirectories under 
                          \100K_DLG.  These subdirectories are named using 
                          the first eight characters of the quadrangle name.  
                          For example, GREENSBO is the subdirectory for 
                          Greensboro.

                          Within each of the subdirectories are four
                          files, one for each data layer.  The file names
                          are in the following format:

                                  XXXYYYYY.ZIP

                          where:

                          XXX   =      Code assigned to the 1:100,000-scale 
                                       quadrangle.  This code and the 
                                       quadrangle name are in the file
                                       FILE.OUT in the DLGSOFT subdirectory.

                          YYYYY =      Layer name:

                                            RAIL  - Railroads
                                            ROADS - Roads and Trails
                                            MTRAN - Miscellaneous
                                                    Transportation
                                            HYDRO - Hydrography

                          ZIP   =      Extension added by the software 
                                       to compress the data.

                          Each of the four files contains the individual
                          data layer files.  There are from 4 to 32 files
                          in a data layer.  Refer to the Data Users Guide 2 
                          section on cell size and file extent for a further 
                          explanation.

                          The data files are stored in a compressed format
                          on the CD-ROM.  The files are automatically
                          decompressed when the data are transferred to the 
                          hard disk.

                                OUTPUT FILE FORMAT

        The file naming convention for output files is as follows:

              AABCCDEE

        AA  = Two-character identification code for the 1:250,000-scale
              quadrangle area of coverage for this file.

        B   = Numeric code representing the quadrant of the 1:250,000-scale
              quadrangle within which the area of coverage falls.
      
                    1=NW     2=NE

                    3=SW     4=SE

        CC  = Indicates the data overlay category

              RD = Roads
              HY = Hydrography
              RR = Railroads
              MT = Miscellaneous Transportation

        D   = Indicates cell size

              S = 7.5-minute
              F = 15-minute

        EE  = Section/cell number within the 1:100,000-scale map
              (see further explanation below)

        Explanation of Section Numbering
      
        The data for each overlay category for a typical 1:100,000-scale
        quadrangle is divided into two 30-minute areas, the east and west 
        halves.  Each half is then further divided into four 15-minute
        sections.  This sectioning scheme is diagrammed below.


                    WEST HALF          ||          EAST HALF          
         ______________________________||_____________________________
        |               |              ||              |              |
        |               |              ||              |              |
        |               |              ||              |              |
        |    Section    |   Section    ||    Section   |    Section   |
        |       1       |      2       ||       3      |       4      |
        |               |              ||              |              |
        |_______________|______________||______________|______________|
        |               |              ||              |              |
        |               |              ||              |              |
        |               |              ||              |              |
        |    Section    |    Section   ||    Section   |    Section   |
        |       5       |       6      ||       7      |       8      |
        |               |              ||              |              |
        |_______________|______________||______________|______________|
                                       ||    
                            SECTION NUMBERING SCHEME
                               Typical Quadrangle


        There are some exceptions to this sectioning scheme.  If the feature
        density in an area is great enough, the file size may exceed the
        limitations of the processing programs used by the production
        centers.  In this case, the 30-minute half is divided into sixteen
        7.5-minute files.  Each half of the quadrangle is evaluated 
        independently.  For example, if the feature density in the west
        half of a quadrangle exceeds the limitations, then only the west
        half will be subdivided into sixteen 7.5-minute files.  The east
        half will retain the typical sectioning.  This policy of assessing
        the data in 30-minute halves results in three possible variations
        of the typical sectioning scheme.  They are diagrammed below.



                    WEST HALF          ||          EAST HALF          
         ______________________________||_____________________________
        |       :       |      :       ||              |              |
        |   1   :   2   |   3  :   4   ||              |              |
        |       :       |      :       ||              |              |
        |-------:-------|------:-------||       3      |       4      |
        |       :       |      :       ||              |              |
        |   9   :  10   |  11  :  12   ||              |              |
        |_______:_______|______:_______||______________|______________|
        |       :       |      :       ||              |              |
        |  17   :  18   |  19  :  20   ||              |              |
        |       :       |      :       ||              |              |
        |-------:-------|------:-------||       7      |       8      |
        |       :       |      :       ||              |              |
        |  25   :  26   |  27  :  28   ||              |              |
        |_______:_______|______:_______||______________|______________|
                                       ||    
                            SECTION NUMBERING SCHEME
                        Quadrangle With a Dense West Half



                    WEST HALF          ||          EAST HALF          
         ______________________________||_____________________________
        |               |              ||       :      |      :       |
        |               |              ||   5   :   6  |   7  :   8   |   
        |               |              ||       :      |      :       |
        |       1       |       2      ||-------:------|------:-------|
        |               |              ||       :      |      :       |
        |               |              ||  13   :  14  |  15  :  16   |
        |_______________|______________||_______:______|______:_______|
        |               |              ||       :      |      :       |
        |               |              ||  21   :  22  |  23  :  24   |
        |               |              ||       :      |      :       |
        |       5       |       6      ||-------:------|------:-------|
        |               |              ||       :      |      :       |
        |               |              ||  29   :  30  |  31  :  32   |
        |_______________|______________||_______:______|______:_______|
                                       ||    
                            SECTION NUMBERING SCHEME
                        Quadrangle With a Dense East Half



                    WEST HALF          ||          EAST HALF          
         ______________________________||_____________________________
        |       :       |      :       ||       :      |      :       |
        |   1   :   2   |   3  :   4   ||   5   :   6  |   7  :   8   |   
        |       :       |      :       ||       :      |      :       |
        |-------:-------|------:-------||-------:------|------:-------|
        |       :       |      :       ||       :      |      :       |
        |   9   :  10   |  11  :  12   ||  13   :  14  |  15  :  16   |
        |_______:_______|______:_______||_______:______|______:_______|
        |       :       |      :       ||       :      |      :       |
        |   17  :  18   |  19  :  20   ||  21   :  22  |  23  :  24   |
        |       :       |      :       ||       :      |      :       |
        |-------:-------|------:-------||-------:------|------:-------|
        |       :       |      :       ||       :      |      :       |
        |  25   :  26   |  27  :  28   ||  29   :  30  |  31  :  32   |
        |_______:_______|______:_______||_______:______|______:_______|
                                       ||    
                            SECTION NUMBERING SCHEME
                 Quadrangle with High Feature Density Throughout


        Additional information about the content and format of the 
        1:100,000-scale DLG files may be found in:
                  Digital Line Graphs from 1:100,000-Scale Maps.
                  (Data Users Guide 2)  U.S. Geological Survey, 1989.


