2.5.11 base.text.s Strikethrough text
The <s> element indicates blocks of text that are no longer relevant.
Example
Markup: base/text/text-s.twig
<span class="xml"><span class="hljs-tag"><<span class="hljs-name">s</span> <span class="hljs-attr">class</span>=<span class="hljs-string">"</span></span></span><span class="hljs-template-variable">{{modifier_class}}</span><span class="xml"><span class="hljs-tag"><span class="hljs-string">"</span>></span>This line of text is meant to be treated as no longer accurate.<span class="hljs-tag"></<span class="hljs-name">s</span>></span>
</span>
Source:
base/text/_text.scss, line 185