Posts Redirections:
This option will determine how to handle post urls; it can take four values :
off, do not redirect post url, whatever the case,
post, only make sure postxx.html is used for a post url,
guest, redirect guests if required to the corresponding topic url rather than to the postxx.html, and only make sure postxx.html is used for logged users,
all, redirect if required to the corresponding topic url.