Date the content expires and is no longer useful or available. For example a <a class="localLink" href="/VideoObject">VideoObject</a> or <a class="localLink" href="/NewsArticle">NewsArticle</a> whose availability or relevance is time-limited, or a <a class="localLink" href="/ClaimReview">ClaimReview</a> fact check whose publisher wants to indicate that it may no longer be relevant (or helpful to highlight) after some date.