at nexus? and other config parameters

[David Cuthbert <dacut@xxxxxxxxx>]

I'm trying to grok the config code to better understand the kernel 
config files -- if anyone can point me to a FM so I can RTFM, I'd 
appreciate it.  The FreeBSD handbook isn't of much help here...

Does anyone understand what "at nexus" and "at nexus?" do?  I'm having a 
bit of an issue trying to untangle the code for this.

Thanks!