The final type of alias is the directory alias. A directory alias is a shorthand reference to a location: a local directory, a network share, even an FTP site. A directory alias name is two or more alphanumeric characters, followed by a colon; or a single digit followed by a colon. The value of the alias should be the complete pathname of the target directory, including a trailing backslash. Don't enclose the name in double quotes, even if it includes spaces.
alias docs:=%userprofile\my documents\
A directory alias can be used like a drive letter in most internal commands. External commands will not understand directory aliases, but you can still use directory aliases when typing external commands; just press Tab, and filename completion will expand the alias into a full pathname. You can also use directory aliases for redirecting input or output, even with external commands. Directory aliases can save you a great deal of typing; define one for any location you access often.