Sometimes it is useful to generate multiple output files from one
template file. UNFUG supports this by changing the output file within an
active `UseTuple'/`EndTuple'. One variable of the tuple defines
the name of the new output file. Usually the template file starts with
where `file' is a variable of the tuple evaluating to a string
containing a valid system specific filename. In addition (using more LISP
code) `output-vos' can be used instead of `output' giving a
system independent file specification under LISP which can be generated
using the standard VLisp functions. Before the new output file is opened
the old one is closed. All output after the `output' statement is
obviously written to the newly created file. This unique feature allows to
generate multiple output files from one template. To check the correct
automatic code generation all output files must be listed in the key
target of the Unfug-Target. If files are missing
VMake will issue an error.