
                                   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
        Florida in the standard distribution format.  The data format is
        the same as that used for distributing the data on 9-track
        magnetic tape.  To use these data on a personal computer or UNIX
        workstation, a carriage return/line feed may need to be added to
        the end of each record.

        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 some preliminary
        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 users 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.

                          ADDCRLF program - Adds a carriage return/line
                          feed (CR/LF) to each record;  some application
                          software needs the CR/LF to determine when a
                          record has been read.

                          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.

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

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

           \DLGSOFT -     Subdirectory containing the executable programs
                          EXTRACT (including graphic files), PKUNZIP,
                          ADDCRLF, and FILEBROW.
                                         
           \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, FT_LAUDE is the
                          subdirectory for Ft. Lauderdale.

                          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 page 20 of the Data
                          Users Guide 2 for a further explanation of
                          the cell size and file extent.

                          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 letter 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 100,000-scale map
              (see further explanation below)

        Explanation of Section/Cell Numbering

        A 1:100,000-scale map can contain 32 7.5-minute cells.  The 7.5-minute
        cells of a 1:100,000-scale map are arranged in longitude tiers,
        8 cells to a tier, numbered as follows:

              ---------------
              |S01...to  S08|
              |S09...to  S16|
              |S17...to  S24|
              |S25...to  S32|
              ---------------
 
        Since the data is sold in 30-minute blocks, the west half of the map
        would contain files S01 to S04, S09 to S12, S17 to S20, and S25 to
        S28. The east half would contain cells S05 to S08, S13 to S16, S21 to
        S24, and S29 to S32.
 
        When a 1:100,000-scale map is digitized, the Hydrography and
        Transportation layers are digitized in 7.5-minute cells.  The
        Railroads and Miscellaneous Transportation layers are digitized in
        30-minute cells.  In order to standardize the cell size of all layers,
        the Hydrography and Transportation layers are panelled together into
        15-minute cells.  The Railroads and Miscellaneous Transportation
        layers are broken up into 15-minute cells.  This whole process is
        called "panelling and partitioning".  When this takes place each
        15-minute cell is edge checked against every adjacent 15-minute cell
        to ensure that if the 15-minute cells were ever joined together, they
        would look like one continuous block of data.

        When the data is grouped into 15-minute cells, the data are numbered
        as follows:

              ---------------
              |             |
              | F01 to F04  |
              |             |
              | F05 to F08  |
              |             |
              ---------------

        The F01 represents a 15-minute cell of data.  The west half would
        contain files F01, F02, F05 and F06.  The east half would contain
        F03, F04, F07 and F08.

        There are some exceptions to this rule.  When an 1:100,000-scale area
        has too much data for a particular layer, the 7.5-minute cells will
        not be panelled together.  The edges for the 7.5-minute cells will be
        checked against all adjacent cells to ensure they match, but they will
        not be grouped together to form a 15-minute cell.  Typically this
        happens in the Hydrography and/or Transportation layers.  When this
        happens, the entire east or west half will contain 7.5-minute cells.

        As an example, the Transportation layer for the Ft. Lauderdale
        quadrangle contains both 15-minute and 7.5-minute cells.  The
        Transportation files in the west half are grouped into 15-minute cells
        and the Transportation files in the east half are grouped into
        7.5-minute cells.

              Ft. Lauderdale

               West       East
              ---------------------------
              |        |                |
              | F01 F02|S05 S06 S07 S08 |
              |        |S13 S14 S15 S16 |
              | F05 F06|S21 S22 S23 S24 |
              |        |S29 S30 S31 S32 |
              |        |                |
              ---------------------------

        Additional information about the content and format of the
        1:100,000-scale DLG files may be found in:

              Digital Line Graph from 1:100,000-Scale Maps.
              (Data Users Guide 2) U.S. Geological Survey, 1989.

