What's an annex? stratum?

[Stan Shebs]

Michael Eager wrote:
> Looking at target.c, I see some terms which are less
> than clear:  annex and stratum.  Could someone tell me
> what these mean?
"Annex" is apparently an introduction of Andrew's from 2004, does kind 
of look like an address space addition, although not clear that it's 
fully implemented.

"Stratum" is an old concept, merely a way to talk about different levels 
of the target stack. In practice, the stacking concept isn't as clean as 
it must have seemed initially; sometimes you really want to run a target 
op in a vector down in the stack, sometimes you want to replace a target 
vector in the middle. So we introduce strata as a way to find a 
mid-stack target vector of a desired type. First big block comment in 
target.h goes into a bit more detail.
>
> Aside:  there are comments in the gdb code which tell me
> that the previous code did things badly and that the new
> scheme is better.  Usually there's no description of the
> new scheme.  I don't know about others, but I find these
> comments are both distracting and unhelpful.
Probably not much consolation, but I'm having the same trouble with 
Mozilla sources these days. :-)

Stan