The command tt(CHDIR) takes one argument, a directory to change to. This
command is implemented to simplify the working with tt(includefile) (see
tt(includefile) in tt(yodlmacros(7))).  As a demonstration,
consider the following fragment:
        verb(
    includefile(subdir/onefile)
    includefile(subdir/anotherfile)
    includefile(subdir/yetanotherfile)
        )
    This fragment can be changed to:
        verb(
    CHDIR(subdir)
    includefile(onefile)
    includefile(anotherfile)
    includefile(yetanotherfile)
    CHDIR(..)
        )
    The current directory, as given to tt(CHDIR), only affects how
tt(includefile) searches for its files. 

    Note that this example assumes that the current working directory is a
member of Yodl's include-path specification (cf., Yodl's tt(--include)
option). 


