\documentstyle
command has been replaced with the \documentclass
command and
that outside packages are included with the usepackage
command.
Another change is that the commands such as {\tt}
have been superseded by
the commands of the form \texttt{}
. LATEX2ealso added the
\textsuperscript
command for use in normal text as an alternative
to using math mode to generate superscripted text. See
Section 12 for several additional sources of information
which are useful in converting documents.