<varname>system</varname> or <varname>security</varname>.
<!-- TODO: Add reference to currently non-existing documentation about
set usage and default sets -->
- After that it will read repository specific configurations from
- <envar>PORTDIR</envar> and <envar>PORTDIR_OVERLAY</envar> that might
- include definitions of sets included in the repository.
+ After that it will read configurations located in repositories
+ configured in <filename>repos.conf</filename>.
Finally a system-specific set configuration may reside in
<filename>/etc/portage</filename> to either define additional sets or
alter the default and repository sets.