From some obscure Windows help file or another, thanks to Alex K. Angelopoulos

Those are all commandline shell replaceable parameters, what are called "batch parameters" in the ntcmds.chm help file which is present on Win2K/XP/2003. They are literally executed as a shell commandline.

Probably the best group for getting info on obscure parameters is microsoft.public.win2000.cmdprompt.admin.

A lot of the more esoteric ones are well-documented in the help file I mentioned;
You can also find the ref online at

Some specifics on the params which ARE documented are here:

Note that in theory you can probably use environment variables in those strings; even though they are REG_SZ values, they are actually executed so they will be expanded automatically.

Below is the batch parameters entry from a WinXP SP1 system's ntcmds.chm file..

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Using batch parameters

You can use batch parameters anywhere within a batch file to extract information about your environment settings.
Cmd.exe provides the batch parameter expansion variables %0 through %9.
When you use batch parameters in a batch file, %0 is replaced by the batch file name, and %1 through %9 are replaced by the corresponding arguments that you type at the command line.

To access arguments beyond %9, you need to use the shift command. For more information about the shift command, see Shift. The %* batch parameter is a wildcard reference to all the arguments, not including %0, that are passed to the batch file.

For example, to copy the contents from Folder1 to Folder2, where %1 is replaced by the value Folder1 and %2 is replaced by the value Folder2, type the following in a batch file called Mybatch.bat:

xcopy %1\*.* %2

To run the file, type:

mybatch.bat C:\folder1 D:\folder2

This has the same effect as typing the following in the batch file:

xcopy C:\folder1 \*.* D:\folder2

You can also use modifiers with batch parameters. Modifiers use current drive and directory information to expand the batch parameter as a partial or complete file or directory name. To use a modifier, type the percent (%) character followed by a tilde (~) character, and then type the appropriate modifier (that is, %~modifier).

The following table lists the modifiers you can use in expansion.

Modifier - Description
%~1 - Expands %1 and removes any surrounding quotation marks ("").
%~f1 - Expands %1 to a fully qualified path name.
%~d1 - Expands %1 to a drive letter.
%~p1 - Expands %1 to a path.
%~n1 - Expands %1 to a file name.
%~x1 - Expands %1 to a file extension.
%~s1 - Expanded path contains short names only.
%~a1 - Expands %1 to file attributes.
%~t1 - Expands %1 to date and time of file.
%~z1 - Expands %1 to size of file.
%~$PATH:1 - Searches the directories listed in the PATH environment variable and expands %1 to the fully qualified name of the first one found. If the environment variable name is not defined or the file is not found, this modifier expands to the empty string.

The following table lists possible combinations of modifiers and qualifiers
that you can use to get compound results.
Modifier - Description
%~dp1 - Expands %1 to a drive letter and path.
%~nx1 - Expands %1 to a file name and extension.
%~dp$PATH:1 - Searches the directories listed in the PATH environment variable for %1 and expands to the drive letter and path of the first one found.
%~ftza1 - Expands %1 to a dir-like output line.

Note
In the previous examples, you can replace %1 and PATH with other batch parameter values.
The %* modifier is a unique modifier that represents all arguments passed in a batch file. You cannot use this modifier in combination with the %~ modifier. The %~ syntax must be terminated by a valid argument value.

You cannot manipulate batch parameters in the same manner that you can manipulate environment variables. You cannot search and replace values or examine substrings. However, you can assign the parameter to an environment variable, and then manipulate the environment variable.