15) : (command)

    DOS uses a leading : to indicate a label.  If the next character
    following the : is a space or other non-alphanumeric char, DOS
    will decide it's an invalid label and skip to the next line,
    performing no further action.

                              Dennis Mccunney
===============================================================================
16) PATH

    With MS-Dos 6.0 you CAN exceed the normal path length limit by
    putting a "Set Path=C:\;..." in your Config.Sys file instead of
    your AutoExec.Bat file.  The usual limits do not apply there.

    I have put in a path well over 800 characters and it works fine.
    The path doesn't display correctly via PATH or SET, but it's in
    there and it all gets searched.

    I don't recommend having a path that long, mine is normally
    only 6-8 directories.

                              Andrew Barnhardt
===============================================================================
17) EDLIN

    where an EDLIN script is:

           -1,#r 1:^Z  1:
           -1,#r 2:^Z  2:
           -1,#r 3:^Z  3:
           -1,#r 4:^Z  4:
           -1,#r 5:^Z  5:
           -1,#r 6:^Z  6:
           -1,#r 7:^Z  7:
           -1,#r 8:^Z  8:
           -1,#r 9:^Z  9:
           e

    Note the spaces (one after R, two after ^Z) which prevent replacement
    of the second digit in a two digit number.

    This will update the last line only, so needs to be done at each
    boot.  '#' means last line +1. '-1' means the line before the current
    one (ie: the last line of the file, if "#" is the current line).  Note
    that you can only use '-1' in later versions (it works in 5, but not
    in 3.30 as far as I know).

                              Mitch Ames
===============================================================================
18) DELIMITING CHARACTER:

    Prior to DOS 5.0, there was an undocumented DOS function that
    would allow you to set the DOS option delimiting character to
    something else, like -.  Once you did this, you could use either
    \ *or* / in PATH specs.

    DOS 5.0 removed the function to *set* the option delimiter, but
    *retained* the one to query what it currently is!  (Don't ask me,
    ask M'Soft...)  Fortunately, the MKS Toolkit still works with no
    apparent glitches.

    I believe in pre-DOS 3.X versions that there was a parm you could
    provide in CONFIG.SYS to do this, but have no further details.

    Just remember: "undocumented" is a synonym for "unsupported, and
    not guaranteed to be there next release", which is what happened
    in the case I mentioned above.

                              Dennis Mccunney
===============================================================================
19) REM IN LINES WITH PIPES OR REDIRECTS

    ie:    REM echo y | del *.*

    Michael Serber reported that he encountered problems when
    he tried to REM out an "echo y|del *.*" line in his batch
    file.  Here is the content of some of the responses he 
    received in response to his question asking why he experienced
    the problem:

    It (the problem) appears to only occur if there is a pipe or
    redirection in the line (REM'd out), leading me to believe that
    DOS first handles pipes and redirections, then goes back to
    find out what to do with them.

                              John Mudge

    It's actually doing what it thinks you've told it: piping the
    output of REM to DEL.  Since REM _has_ no output (remember
    REM > NULLFILE?), DEL hangs, waiting for the answer to its
    question.

                              Gary Smith

    What is happening here is that DOS reads the entire line, and
    always processes redirection and piping *first*, regardless of
    where they happen to appear.

                              Dennis Mccunney
===============================================================================