How to set facebook group tags (post_tags)?

Question

Facebook

Please tell me,
How to tag posts in a facebook group (add so-called post_tags, not hashtags)?
Group:

• type: public
  
• Privacy: Secret
  

At the top right of the post in the drop-down menu (as everyone advises) there are no corresponding control buttons. I looked through all the documentation and tutorials, but I can’t find an answer.