You can use the datetime-design-pattern to publish both a human and machine readable by applying this code in your WordPress template within The Loop replacing the_time or the_date:
<abbr class="published" title="<?php the_time('Y-m-d\TH:i:sO'); ?>"><?php the_time('F jS, Y g:i a'); ?></abbr>
when apply this, is that mandatory to name the class as published?
can i use pubDate instead?
Depends because class
published(entry published) is part of hAtom schema.Just take note, that previous version of IE doesn’t support
<abbr>. Styling it could be PIA. Wrap it up with<div>or<span>.