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Scroll down to Post Expirator on the right side of the edit screen.
Check Enable Post Expiration to set an expiration date.
Choose a date and time at which you would like your post to expire and choose what happens to the post upon expiration. You have the following options:
Change its status to Draft.
Delete the post.
Change the post's visibility to Private.
Update the post's category (Replace, Add, Remove).
Click Update to save your changes.
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Below is an example of what the SASS Tag page looks like with Full Text chosen vs with Summary chosen. The Child Theming with SASS page has an excerpt, whereas the Child Theming with CSS page does not.
  SASS Tag Page: Full Text |   SASS Tag Page: Summary |
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