INDEX isn't available in non-VM 1.8b.  It will be available in 1.8c.
 
On Mon, 13 May 1996 08:17:11 EDT John Witherspoon said:
>Dear All,
>
>I am running a list using version 1.8b on an AIX platform.  For some
>reason, anyone trying to set their subscription to INDEX gets an
>"invalid subscription option" (or something like that) message.
>
>Any clues as to why this is and what can be done to fix the situation?
>
>-- John Witherspoon