+- `to`: A list of nicknames (like `lain@soykaf.club` or `lain` on the local server) that will be used to determine who is going to be addressed by this post. Using this will disable the implicit addressing by mentioned names in the `status` body, only the people in the `to` list will be addressed. The normal rules for for post visibility are not affected by this and will still apply.
+- `visibility`: string, besides standard MastoAPI values (`direct`, `private`, `unlisted` or `public`) it can be used to address a List by setting it to `list:LIST_ID`.
+- `expires_in`: The number of seconds the posted activity should expire in. When a posted activity expires it will be deleted from the server, and a delete request for it will be federated. This needs to be longer than an hour.
+- `in_reply_to_conversation_id`: Will reply to a given conversation, addressing only the people who are part of the recipient set of that conversation. Sets the visibility to `direct`.