In the section on banning OpenID users, there are still some remnants of the time before the move to subdomains for everyone.
Specifically, it mentions that the URL for 'more details' will be something like ext_1.livejournal.com/profile?mode=full -- however, the URL will have hyphens, not underscores, so it'll be ext-1.livejournal.com/profile?mode=full (see, for example, http://www.livejournal.com/userinfo.bml?userid=9821956&t=I for a random example).
Also, The name immediately following "user" in that URL should probably become something like The name immediately before ".livejournal.com" in that URL, since the word user doesn't appear in the URL any more. (That must have been from the times of http://www.livejournal.com/userinfo.bml?user=exampleusername.)
Also, possiby replace in this example, ext_1. It will always start with "ext_". with in this example, ext-1. It will always start with "ext-". to show that there'll be hyphens, rather than underscores, in the URL.
I'm less sure what to do with the example admin console command, ban_set ext_1 -- whether to leave it and say 'please convert the hyphen to an underscore', whether to leave it without comment on the fact that it's got an underscore while the URL has a hyphen, or whether to change the command to ban_set ext-1, with a hyphen. Whichever you choose, the final sentence should reflect the command (i.e. mention replacing either "ext_1" or "ext-1" with the actual system name).
For what it's worth, it seems that ban_set ext-4325 works in the admin console as well; 'ban_list' shows that I've banned 'ext_4325'.
So it might be easiest just to use hyphens throughout, since that may confuse people less than having to read one character from the URL but enter another in the admin console. (On the other hand, they may wonder why OpenID users 'get to use' hyphens in their system names while they 'have to use' underscores... but they may also think that OpenID users' usernames are simply weird.)