In options.txt for Vim version 8.2 can be found the following:
E992
No other commands than "set" are supported, for security reasons (somebody
might create a Trojan horse text file with modelines). And not all options
can be set. For some options a flag is set, so that when the value is used
the sandbox is effective. Some options can only be set from the modeline
when 'modelineexpr' is set (the default is off).
There seem to be a great many options in Latex-Suite that can be set from the modeline, if it is enabled, and I can't imagine its authors have created a Trojan horse, and
~/.vim/doc/latex-suite.txt has three modeline expressions on its last three lines. Without set modelineexpr on you get that E992 message when asking for latex or latex-suite help in vim. However, this option is not known outside latex-suite, at least not in the way I use vim, so just enabling it in .vimrc creates error warnings when using vim to edit non-tex files, such as .vimrc itself. I use vim for a great many editing tasks other than LaTeX document creation, in fact, I am embarking on using vim in this manner for the first time, comparing it with TexShop and texmaker to see which I prefer (I volunteered as a math tutor at a local community college.) I hate error and warning messages, especially after an install. They assert something is very wrong, either with the install or with the package. I won't use a product until all of the early error or warning messages are eliminated, and at some point I'm going to have to guide my students through an install of whichever product I choose. In addressing this problem I discovered Vimscript. Man, is that implementation impressive. emacs, you have finally met your match!
So, to solve the E992 problem in latex-suite, and to prevent a related problem when using vim for Perl or C, I added this Vimscript expression to my .vimrc, to wit:
" This conditional is needed to suppress E992 error in latex-suite.
if &filetype ==# 'plaintex'
set modelineexpr on
endif
plaintex is the filetype vim assigns to *.tex files.
If Latex-suites' authors, or any other vim/tex gurus think this is a stupid solution, please comment. I can imagine a <leader> key mapping to toggle this option on and off, except I'm happy with my solution. It's very visible, whereas that command would not be, and one would have to remember to toggle it on before asking for help. Otherwise, I will mark this problem solved at the appropriate time.
