The next commands in the preamble are specifically designed to differentiate LaTeXe documents from those needing LaTeX 2.09.
This command or ``declaration'' replaces the LaTeX 2.09 command \documentstyle.
There must be exactly one \documentclass declaration in a document, and it must come first (except for the ``initial'' commands described above).
option-list: list of options that each can modify the formatting of document elements defined in the class-name file or in packages loaded with \usepackage declarations, as described below.
class-name: name of the class file (file extension
release-date (optional) specifies release date of the
class file, using the format
If a version of the class older than this date is found,
a warning is issued.
This command, which is supported for compatibility reasons, is similar to \documentclass, but it loads a ``compatibility mode'' which redefines certain commands to act as they did in LaTeX 2.09 and thus allows you to run your old files unchanged through LaTeXe. Note, however, that in this mode, you cannot use any of the LaTeXe extensions described in this article.
You can define new or change existing document elements by loading package files with \usepackage, whose syntax is:
package-name: name of the package (file extension
a package can
option-list: list of options, each of which can modify the formatting of elements defined in the package.
release-date: (optional) earliest desired release date of package file (see \documentclass command above).
Any number of \usepackage are allowed, but LaTeXe makes sure that each package is loaded only once. On top of processing the list of options specified in the argument option-list on its \usepackage command, each package also processes the option option-list on the \documentclass command.
To help you get an overview of the files read in by your document during processing, you can place a \listfiles command in the preamble of your document. This will display the list of all files used at the end of the run. An example for (part of) the production of this CNL would show something like in figure .
: Example output of \listfiles command