Entering LaTeX 2.09 COMPATIBILITY MODE
followed by lines of asterisks and !!WARNING!!.
.dvi or .pdf that’s
adequate for most purposes.
If it’s a new document you have just started working on, you have been
misled by someone. You have written something like:
\documentstyle{article}
or, more generally:
\documentstyle[options]{class}
These forms are (as the warning says) LaTeX 2.09 syntax, and to get rid of the warning, you must change the command.
The simple form is easy to deal with:\documentstyle{article}
should become:
\documentclass{article}
The complex form is more difficult, since LaTeX 2.09 “options”
conflate two sorts of things — options for the class (such as
11pt, fleqn), and packages to be loaded.
So:
\documentstyle[11pt,verbatim]{article}
should become:
\documentclass[11pt]{article}
\usepackage{verbatim}
because 11pt happens to be a class option, while
verbatim is a package.
10pt,
11pt, 12pt, draft,
fleqn, leqno, twocolumn and
twoside — anything else must be a package.
Your document may well “just work” after changes like those above;
if not, you should think through what you’re trying to do, and consult
documentation on how to do it — there are lots of
free tutorials to help you on your way, if you
don’t have access to a LaTeX manual of any sort.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=entercompmode