Here's a simple block:

    foo

    This should be a code block, though:

    1. <div>
    2. foo
    3. </div>

    As should this:

    1. <div>foo</div>

    Now, nested:

    foo

    This should just be an HTML comment: Multiline: Code block:

    1. <!-- Comment -->

    Just plain comment, with trailing spaces on the line: Code:

    1. <hr />

    Hr's: