## The Preamble and MODE tag

Each mode definition must begin with the following:

    <?xml version="1.0"?>
    <!DOCTYPE MODE SYSTEM "xmode.dtd">

Each mode definition must also contain exactly one `MODE` tag. All other tags (`PROPS`, `RULES`) must be placed inside the `MODE` tag. The `MODE` tag does not have any defined attributes. Here is an example:

    <MODE>
        ... mode definition goes here ...
    </MODE>