Continuing the process of learning how to turn my regular comments into proper Doxygen comments. I'm still working on the db_fields.php file, which is substantial and has multiple classes in it. I've also been trying to work out how to get PDF documentation out of Doxygen; it generates a Latex project with a Makefile, but when I run Make on the directory, it fails to find the command pdflatex. I can't find a package by that name, or any package which is supposed to contain it, so I'm installing as many core Latex-related packages as I can find. We shall see. Maybe nobody uses the PDF output any more, but it would be handy for e-readers and printed output.