+=head1 ROOTS (FILES AND DIRECTORIES)
+
+Each parameter should refer to a file or directory which is to be
+included in the installer.
+
+These are known as "roots" because we also automatically add any
+dependencies to the list of files. Thus if a Windows executable
+requires any DLLs, those are added automatically. DLLs are searched
+for on the current C<$PATH> (environment variable).
+
+We choose the install location by removing any common prefix from the
+names of roots, which generally ensures that the original directory
+structure is preserved. Thus for example if the original roots (and
+any dependencies) are:
+
+ /usr/i686-pc-mingw32/sys-root/mingw/bin/program.exe
+ /usr/i686-pc-mingw32/sys-root/mingw/bin/library.dll
+ /usr/i686-pc-mingw32/sys-root/mingw/etc/config
+
+then the install directory will look like this:
+
+ $INSTDIR/bin/program.exe
+ $INSTDIR/bin/library.dll
+ $INSTDIR/etc/config
+
+(C<$INSTDIR> is the installation directory chosen by the user at
+install time).
+
+You can also specify the install location (relative to C<$INSTDIR>) by
+adding roots of the form:
+
+ source=destination
+
+for example:
+
+ /usr/i686-pc-mingw32/sys-root/mingw/bin/program.exe=program.exe
+ /usr/i686-pc-mingw32/sys-root/mingw/bin/library.dll=library.dll
+ /usr/i686-pc-mingw32/sys-root/mingw/etc/config=conf/config
+
+which results in:
+
+ $INSTDIR/program.exe
+ $INSTDIR/library.dll
+ $INSTDIR/conf/config
+