what is systems programming?

[Mayuresh Kathe <mayuresh%sdf.org@localhost>]

i have been a programmer since 1991, but have
always written applications, mostly with c++.
i don't have any formal training in the field
of computer science, though i do have a
professional diploma in network centered
computing; something which would be called a
community college education is the united
states.
i have heard a lot of references to systems
programming throughout my time as a
programmer in the past 30 years, but even
on inquiring haven't received a clear and
simple answer to what makes a systems
programmer.
would you be kind enough to share your
views about what would make a systems
programmer under netbsd?
is a person who write kernel code to be
categorized as a systems programmer?
or is anyone who writes code interfacing
userland to the kernel called a systems
programmer?
thanks in advance.