Forum posting
From MoodleDocs
Note for Contributors This page should explain what can be seen on the moodlesite.com/mod/forum/post.php page (when posting a new forum message)
Posting a forum message, you will find several fields to complete.
The default content of Subject is usually 're: <the name of the 'parent' post>'. You can change it though.
Message
Formatting
Subscription
Attachment