MBUNITS             You have two choices for specifying and/or printing distanceand elevation values:                                                                                                     (B)ritish units: feet and miles                                                                                         (M)etric units:  meters and kilometers                                                                                
HORUNIT             You have three options for saving the locations of the pointelevation values from the elevation data base:                                                                            þ Distance - The locations can be saved as distance valuesof each location from a user-specified reference location.  The units used (miles or kilometers) are determined by the  current setting of the system of units (British or metric).                                                               þ Lat/Lon coordinates - The locations can be saved using  the latitude and longitude values of each location.                                                                       þ UTM coordinates - The locations can be saved using the  Universal Transverse Mercator (UTM) coordinates (in         kilometers) of each location.                                                                                           The number  of miles  per degree  latitude and the number ofmiles per  degree   longitude are  usually not  equal.  (Forexample, a  7-1/2 minute  topo map  is not  square,  becausedistances for 7-1/2 minutes of latitude and 7-1/2 minutes oflongitude   are    not   equal.)   Therefore,   the   visualrepresentation of  the terrain  will be  more accurate usingeither the distance or UTM option instead of the Lat/Lon    option.  Using  degrees of  latitude and  longitude as the  units  will  result  in  the  plot  of  the  data  appearingcompressed in  the north-south  direction. (Picture  a 7-1/2minute map  squeezed to  make the  vertical size the same asthe horizontal size.)                                                                                                   However, for  some mapping  applications, use  of the actuallatitude  and  longitude  values  may  be  more  convenient.Although the default setting for this  program is the use ofdistance units,  you may elect to write the file  using lat-itude and longitude values.                                                                                                   Please note:      The standard convention for plottingdata along  the X-axis   (horizontal) uses increasing valuesfrom  left   to  right,  but  standard  mapping  conventionsincrease the values of longitude going from the right to theleft.                                                                                                                   Therefore,  the  longitude  (X-axis)  values  saved  in  theSURFER(tm) .GRD  file are  forced to negative values to makethe orientation  of the plotted data conform to normal maps.The negative  values marked on the X-axis should be ignored,or, after  you create  an ASCII (not binary) .PLT file usingSURFER(tm) you  may edit the PS commands ( Plot String ) forthe X-axis  labels to remove the '-'  sign. (Only remove the'-' sign  inside the double quote (" ") marks to change the LABEL value.  The other '-' signs are the actual coordinatesfor the   plotter,  which must  be negative  to maintain theproper map orientation.)                                                                                                If you select the UTM coordinate option all UTM values (in  kilometers) will be referenced to the UTM zone of the       southwest (lower left) corner of the specified rectangular  area, even if the area extends into another UTM zone.                                                                   
MKPATH              The "target" files created by this program (grid, posting,  boundary line, X-Y-Z data) can be written to any valid DOS  path and file name.                                                                                                     If you want to write these file into the path with the otherfiles for the current JOB (label file, site file, etc.) a   new path must be created for new JOB numbers, and you shouldrespond "Y" to this question.                                                                                           If you always want to write these files into a particular   path (e.g., \SURFER with the SURFER(tm) software) you shouldrespond "N" so the default path you last specifed will be   saved.                                                                                                                  Note that can change the path and file names after the JOB  or default path has been created by the program.                                                                        
REFPOINT            Enter the reference point (latitude and longitude) to use incomputing distances for the elevation points in the grid    file.  You can enter the coordinates directly, or you can   automatically insert coordinates using the function keys:                                                                 þ Press <F2> to insert the coordinates of the lower left  (southwest) corner of the rectangular area.  (This was the  standard reference for earlier versions of TAP.)                                                                          þ Press <F4> to retrieve the primary site coordinates for the current JOB number.  This will enable you to use the    topographic data grid file created by this program to be    used with other files created by TAP, such as field strengthcalculations which reference the computed values to the     site.                                                                                                                   
CORNERS             This program is used to extract data from the topographic   data base files for a user-specified rectangular area.  The resulting data file can be used by other software (such as  SURFER(tm) from Golden Software) for plotting the terrain.                                                              You have three ways you can specify the corner (SW and NE)  coordinates of the area:                                                                                                     þ You can enter the coordinates directly, based on the        area you want to include.                                                                                             þ You can press <F9> to open a window that allows you         to enter either UTM coordinates or measurements             (inches or millimeters) from a map that will be             converted to the corresponding latitude and longitude       values.                                                                                                               þ You can press <F3> to compute the coordinates based         on a specified distance from a central site.  This          will compute the SW and NE corner latitudes and             longitudes of the area necessary to include the given       distance from the site.                                                                                          
BADXY               The corner boundaries you have specified include regions    with different resolutions in the topographic data base you have specified.                                                                                                         For example, the USGS "3-second" DEM data base for Alaska   actually has a longitude resolution of 6-arcseconds up to   70ø latitude, but a resolution of 9-arcseconds for 70ø      latitude and farther north.                                                                                             Because the boundaries you have specified have unequal      resolutions in at least one direction, you cannot make a    single SURFER grid (.GRD) file or a single X-Y-Z file with  these boundaries using this program.  You must change the   southwest and/or the northeast corners you specified to staywithin a region of uniform data resolution.                                                                             
DSKCHG              This program will look for the required elevation data base files according to the paths specified in the system        configuation screen. These paths (primary and alternate) arenormally specified as the hard disk or CD-ROM drive.                                                                    If the required file is not found in either of these paths, the program can prompt you to insert the required floppy    disk or CD-ROM disk.                                                                                                    However, you also have the option of suppressing this promptasking for another disk.  For example, if you want to       extract a large amount of data without interruption, answer "N" to this prompt. During the data extraction for each datapoint, if a data file is not found, no prompt will will be  issued for a disk.  A dummy value (specified by you) will beinserted into the area data file.                                                                                       If you do not want to stop to change disks, the dummy value should be selected to ensure that areas where data files    were not available will be obvious.  A value of zero (0) canusually be used, except in coastal areas.  To distinguish   actual zero (sea level) elevations from unkown elevations   where data files are not available, you should select a     different dummy value, such as -1000, to mark areas where   elevations were not available.                                                                                          
DENSITY             You may specify  a "density factor" for the data points.    This density factor enables you to sample large areas of    topographic elevation data and create a grid using only     a portion of the data to represent the area.  You may chooseto use only every  2nd, or 3rd, or 9th, etc., data point    from the terrain data base.  This will reduce the number    of data points to be processed, and may provide adequate    resolution if you are interested in a large geographical    area.                                                                                                                   
GRIDNAME            Enter the complete path and file name of the GRID file to becreated.                                                                                                                
POSTNAME            Enter the complete path and file name of the POSTING data   file to be created.  This is a file that can contain        location and label information to be added to the plot of   the grid file using third party software.                                                                               If you want to copy the path information from the grid file name to make the posting data file name, press <F2>.                                                                    Later in this program, you will be able to enter coordinatesand a description for each point you want to label.  If you do not want to include posting labels with this grid file   you can ignore this feature.                                                                                            Note that the posting data file you create must be based on the same system of units and corner coordinates specified   for the grid file the posting data is to be used with.                                                                  
LINENAME            Enter the complete path and file name of the BOUNDARY data  file to be created.  This is a file that can contain        boundary line information to be added to the plot of the    grid file using third party software.                                                                                   If you want to copy the path information from the grid file name to make the boundary data file name, press <F2>.                                                                   Later in this program, you will be able to enter coordinatesof the vertices of the boundary or line you want.  If you donot want to include boundary lines with this grid file you  can ignore this feature.                                                                                                Note that the boundary line file you create must be based onthe same system of units and corner coordinates specified   for the grid file the boundary line file is to be used with.                                                            
GRID FOR POST       The posting data file you create must be based on the same  system of units and corner coordinates specified for the    grid file the posting data is to be used with.                                                                          Enter the name of the grid file that the posting file will  be used with.  The file must be an ASCII grid file created  with this software.  (Binary grid files, or grid files      created with other software will not contain the needed     information about units, reference points, etc., necessary  to register the posting file with the grid file.                                                                        
GRID FOR LINE       The boundary data file you create must be based on the same system of units and corner coordinates specified for the    grid file the boundary data is to be used with.                                                                         Enter the name of the grid file that the boundary file will be used with.  The file must be an ASCII grid file created  with this software.  (Binary grid files, or grid files      created with other software will not contain the needed     information about units, reference points, etc., necessary  to register the boundary file with the grid file.                                                                       
1CORNERS            This function allows you to return to the "Area Data        Extraction Parameters" screen to set the area corner points,horizontal units, disk change switch, etc.                  
2MAKEGRID           This function creates an output file in the selected grid   (.GRD) format that can be used by the other third-party     programs for two- or three-dimensional plotting.  For more  information on the grid format, see the plotting software   manual.                                                     
3POSTFILE           This function enables you to create a "posting" file for usewith the grid file created with this program.  The posting  file (sometimes called a sample point or label point file)  enables you to locate and mark specific locations on the    plot of the gridded information.  Note that this posting    file uses the same units and reference point as the grid    file created by another function of this program, and the   posting file can ONLY be used with the grid file it was     created for.  Using a posting file created for one grid filewith a different grid file (with different units and or     reference points) will cause incorrect results.                                                                         While this program provides a basic function to create the  data for posting locations on gridded plots, the SoftWright Boundary Line module provides a significantly more          sophisticated editor for creating labeled point locations,  as well as lines or closed boundaries that can be used for  the same types of posting files.                                                                                        
4LINEFILE           This function enables you to create a "boundary" file for   use with the grid file created with this program.  The      boundary file enables you to draw lines and closed          boundaries on the plot of the gridded information.  Note    that this boundary file uses the same units and reference   point as the grid file created by another function of this  program, and the boundary file can ONLY be used with the    grid file it was created for.  Using a boundary file createdfor one grid file with a different grid file (with differentunits and or reference points) will cause incorrect results.                                                            While this program provides a basic function to create the  data for boundary lines on gridded plots, the SoftWright    Boundary Line module provides a significantly more          sophisticated editor for creating lines or closed           boundaries, as well as labeled point locations that can be  used for the same types of boundary files.                                                                              
5SWELSRGQUIT        This choice will end this session of the program and return you to the system menu.                                                                                                 
SWELSRGGENERAL      This program  is used  to extract  point elevation data fromthe National  Geophysical Data Center (NGDC) 30-second pointelevation data  base, or  from the  U.S.  Geological  Survey(USGS) 3-second Digital Elevation Model (DEM). The extracteddata can be written as a standard  ASCII X-Y-Z data file, orthe data can be written as a "GRID" file for use by the     SURFER mapping and 3-dimensional graphics software.                                                                     If you  wish to extract the data for other purposes (such ascomputing Height Above Average Terrain for radio propogationstudies)  exit   this  program   and  execute  the   TERRAINELEVATIONS FROM DATA BASE program.                                                                                          The  file for  SURFER consists  of a  grid of  elevationvalues enclosed  by a   user-specified  rectangle . In orderto define  this rectangle you must  specify the latitude andlongitude of  two opposite  corners.  You  must  know    thecoordinates of  the LOWER  LEFT (southwest)  corner, and theUPPER RIGHT  (northeast) corner of the rectangle.                                                                       This program will then retrieve pertinent data from the NGDCdata base and  write a an ASCII file in the .GRD format usedby  the   SURFER  programs   to    provide  a  3-D  graphicspresentation on  the screen,  or a  SURFER supported    dot-matrix printer or plotter.                                                                                              Only the  actual elevation data points contained in the NGDCor  USGS  file  are  used, and no interpolation is performedby this program. The grid information  saved consists of thedistance east  of the  lower left  corner (X-axis)  and  thedistance north  of  the  lower  left  corner  (Y-axis).  Therelative distances  (in   miles or  kilometers)  are  storedrather than  the actual  Latitude and  Longitude   to give amore representative  visual presentation  of the data, sincethe  Latitude/Longitude aspect ratio is not unity and varieswith Latitude.                                                                                                          
FIRSTPOINT          You specified "NO" for the disk change option during this   session, and the file needed for the FIRST data point was   not found.  When disk change is disabled you should be sure that the file(s) for the area are on the hard disk, or that the correct CD-ROM is in the drive.  If you extract area    data with disk change disabled and none of the needed files are found, the resulting file created by this program will  consist of ALL dummy values (specifed when you disabled the disk change option).                                                                                                    You have two options:                                                                                                     Press <F10> to continue this data extraction.                                                                           Press <ESC> to exit and change program parameters, enable   disk change, try again with the correct CD-ROM ,etc.                                                                  
AREAFORMATS         This program allows you to write the output format of the   area elevation data in any of the three formats shown:                                                                    þ SURFER (Golden Software)                                  þ GRIDZO (RockWare)                                         þ X-Y-Z (three columns of comma-delimited values)                                                                     Select the format you want to use.  For more information on the SURFER or GRIDZO formats, refer to the documentation forthose programs.                                                                                                         
G30FILEFORMAT       This program allows you to write the output format of the   area elevation data in any of the formats shown:                                                                          þ SURFER (Golden Software)                                  þ GRIDZO (RockWare)                                         þ X-Y-Z (three columns of comma-delimited values)                                                                     If you want to write the output as an X-Y-Z file you have   the choice of writing the X and Y values as UTM or latitude and longitude coordinate values.  (The SURFER and GRIDZO    format files are written as UTM values.)  The Z (elevation) values are written as meters in all cases.                                                                              Select the format you want to use.  For more information on the SURFER or GRIDZO formats, refer to the documentation forthose programs.                                                                                                         
