Prevent the slug of a trashed page or post from conflicting with the slug desired for a new page or post. NOTE: NO LONGER NECESSARY AS OF WORDPRESS 4.5.

Customization with hooks Use of filter hooks is at your own risk.

Blocks URL modifications if post is already public. URL can still be modified if the article is a draft.

Allow long permalinks in your WordPress. Useful especially for using non-latin characters in permalinks. Respects future relevant core updates.