generate top-level pkg install list?

[Gary Aitken]

I'm having trouble figuring out how to generate a top level list of packages
to install.  In the past, I've worked off a manual list, but as I've added a
few things over time I'm wondering if it's possible to generate such a list
from the pkg output.

In the past I've used portmaster to get at top-level packages but I'm trying
to avoid portmaster and stick with pkg.

Any ideas for how to generate a list of packages installed deliberately and
in sequence?

Thanks,

Gary