double quotes <code>""</code> or back quotes <code>``</code>.
</p>

<p>
The form <code>a … b</code> represents the set of characters from
<code>a</code> through <code>b</code> as alternatives. The horizontal
ellipsis <code>…</code> is also used elsewhere in the spec to informally denote various
enumerations or code snippets that are not further specified. The character <code>…</code>