#File:  A collection of related information stored on disk and treated as a
unit.  A file is identified by its filename and optional filename extension.
#Filename:  A one- to eight-character string which identifies a file.  Each file
must have a filename and may have a one- to three-character filename extension.
 
The following characters may be used in a filename:
 
     A-Z, 0-9, and the symbols: $ # & @ ! % ' ` ( ) - { } _ ^ ~
 
     All other characters are invalid.
 
See FILESPEC and FILENAME EXTENSION for related information.
#Filename Extension:  A one- to three-character suffix to a filename.  The
extension is optional.  When used, it must be separated from the filename by a
period.  The file MYFILE.DAT has the filename extension "DAT".  Extensions are
useful to add meaning to the filename.  Certain extensions have special meaning
to DOS.  For example, BAT is used for batch files, COM for command files and EXE
for executable programs.
 
The following characters may be used in a filename extension:
 
     A-Z, 0-9, and the symbols: $ & # @ ! % ' ` ( ) - { } _ ^ ~
 
     All other characters are invalid.
 
See FILENAME and FILESPEC for related information.
#Filespec:  Stands for File Specification.  A filespec completely identifies
a file to DOS.
 
A filespec has the form:
 
   [d:] [path] filename[.ext]
 
   where    d:     = the letter of the drive where the file can be found. If the
                     file is on the default drive, "d" may be omitted.
          path     = the "directory path," which tells DOS which subdirectory,
                     if any, the file is in.  If the file is in the current
                     directory, "path" may be omitted.
          filename = the filename of the file.
          .ext     = the filename extension of the file, if one exists.
 
See DEFAULT DRIVE, FILENAME, FILENAME EXTENSION and DIRECTORY PATH for
related information.
#Filter:  A program or command that receives data from a standard input device,
changes the data and writes the results to a standard output device.  The
commands SORT, FIND and MORE are filters.  The filtering is accomplished via
piping (program chaining using "|" between commands) or redirection (with <, >
or >> ).
 
Examples:  TYPE MYFILE | MORE        Displays the contents of MYFILE and halts
                                     the computer when the screen is full.
 
   SORT < MYFILE > MYFILE.SRT        Sorts MYFILE and writes the sorted output
                                     to the file MYFILE.SRT.
 
See CHAINING COMMANDS, PIPING AND REDIRECTION for more information.
 
See PIPING and REDIRECT in the ADVANCED menu for detail usage information.
#Fragmented File:  A file that has many discontiguous (non-sequential or
fragmented) sectors.  DOS tries to allocate a file's data in contiguous areas,
but cannot always do so if many files have been erased and added to the disk.
Fragmented files take longer to access, since DOS cannot read them sequentially.
 
The CHKDSK command will display files with discontiguous sectors.  To obtain a
list of fragmented files enter:   CHKDSK *.*
 
If the fragmented file is on diskette, you can cure the fragmentation by
copying all the files onto a newly formatted diskette (using the COPY command).
When the files are copied, DOS will allocate data in contiguous areas, thus
relieving fragmentation.  You may then either use the new diskette instead of
the original or you can use DISKCOPY to copy the new diskette's files back to
your original diskette.  Note that this does not change the names of the files
or their contents.
#Global Filename Characters (* and ?):  The asterisk (*) may be used in a
filename and filename extension.  It means any character can be in the position
of the *, and in the remainder of the filename or extension.  This global
character lets you specify many files in one command.
 
For example, by using the * with the DIR command, you could see all files that
have the filename extension of DAT by entering:
 
    DIR *.DAT
 
To see all files whose name begins with BUD enter:
 
    DIR BUD*
 
To see all files whose filename begins with BUD and whose extension begins with
8, enter:
 
    DIR BUD*.8*
 
 
The global character (?), sometimes called a "wildcard," may be used in a
filename and filename extension.  It means "any character in this position."
 
For example, by using ? with the DIR command, you could see all files with an
eight character filename that begins with BUDGET and has a filename extension of
DAT by entering:
 
    DIR BUDGET??.DAT
 
The seventh and eighth positions of the filename may have any characters.
#Halt System:  To halt the computer.  DOS has three facilities which halt the
computer until any key is pressed:
 
1. Hold down the CTRL key and press the NUM LOCK key.  This will halt any
operation.
 
2. Chaining MORE to a command will cause display scrolling to halt when the
screen is full.
 
   EXAMPLE:
 
      DIR | MORE
 
   Note: With the DIR command, the preferred way to halt the computer when the
         screen is full is to add /P to the end of the command, as in DIR /P.
 
3. A batch file can be halted by inserting the Batch Subcommand PAUSE in the
batch file.
#Internal Command:  A DOS command that is stored in memory and may be executed
without requiring a diskette containing DOS to be in use.  The most commonly
used commands, such as DIR, ERASE, CHDIR, DATE, RENAME (and others) are
internal commands.  This is distinguished from "external commands" which reside
on disk.
 
See also EXTERNAL COMMAND.
