You can use system environment variables enclosed in percent signs in directory entries to specify information. For example:

"%%windir%\notepad.exe"

starts Notepad, the %%windir% being substituted by the path to your Windows directory (usually "c:\windows").

Bout note that the example illustrates a special rule. An environment variable, or the first of a sequence of consecutive environment variables, must be preceded by an extra percent sign. This is because the percent sign is also used to embed WintextCom functions, which treat a percent sign as specifying that the ensuing text is an environment variable terminated by the closing percent sign. Thus the first of any sequence of environment variables must start with a double percent sign, but subsequent environment variable specifications in the same string of text being processed should just be enclosed in single percent signs, as normal.

You can included environment variables in the program or document specification at the beginning of a directory entry, in the startup directory specification (if any), and in command line parameters.

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System Environment Variables