-P: Select TeX processor
Say -PT or -PL to inform FWEAVE that its output will
be processed by TeX or LaTeX, respectively. Beginning with
Version 1.50, the default processor is LaTeX (-PL). If you
always use TeX, it's easiest to put -PT into the .fweb
initialization file.
Please note that -PT is no longer supported; FWEB
development is now based exclusively on LaTeX.