A bit confused with the sched_4bsd.c code

[Halil Demirezen]

Hello,

First of all, I am not sure if this is the correct mail list with posting this 
mail. I apologize for that.. Second, I may seem to have little 
C knowledge, though I am using C for about 5 years and plus.

Let's start with the question. I am digging the FreeBSD-5.3 kernel codes.
Watson's Cross Reference is really helpful. In the schedcpu(void) function
there is an assignment like "ke = td->td_kse;" on line 438  (see: 
http://fxr.watson.org/fxr/source/kern/sched_4bsd.c?v=RELENG53#L438").
When I look at the thread structure at sys/proc.h, I could not see such an
entry td_kse in the "thread" structure. How has this structure been extended 
or this entry added to the thread structure?

Although the kernel codes seem to be simply understandable, there still lies
some difficulties to understand for an average C programmer: magic stuff done
by professionals. :)

Anyway, any help really will be appreciated...

Thanks.