If you want to produce one or more LaTeX documents, you need to add a LaTeX header at the beginning of your file (only one header should be used in a file even in a multiple modules file). A LaTeX header look like this:
tex title = "A Short proof of Fermat's last Theorem" author = "Donald Duck" institute = "University of Dingo-city" documents = math slides.
The three first fields are self explanatory and the strings can contain any
valid LaTeX text which can be used as argument of the \title of
\author commands.
The last field is a list of documents that will produce. In this case, if
this header appears in a file fermat.phx, the command
phox -c fermat.phx will produce two files named fermat.math.tex
and fermat.slides.tex.
The document names math and slides will be used later in
LaTeX comments.
Warning: do not forget the dot at the end of the header.