Handles showing the post screen, loading the post to be modified, and loading any post quoted. Also handles previews of posts.

• Uses the Post template and language file, main sub template.
• Allows wireless access using the protocol_post sub template.
• Requires different permissions depending on the actions, but most notably post_new, post_reply_own, and post_reply_any.
• Shows options for the editing and posting of calendar events and attachments, as well as the posting of polls.
• Accessed from ?action=post.