'Posting’ in the pen world refers to what you do with your pen cap while you write [. . .] when you put the cap on the back of the pen while you write, regardless of whether it pushes on or screws on with threads.
[. . .] what do you do with the cap? Do you put it on the desk? Hold it in your hand? Both of these would be ‘non-posting’ or ‘unposted’ writing methods.
I write unposted, have done so my whole life, and think that people who post are weird, pitiable, and simply wrong.