gentoo's package.provided equivalent?

[Anatoly]

В Mon, 4 Apr 2016 09:01:44 +0100
Matthew Seaman <matthew at freebsd.org> wrote:

> I could be wrong though -- the only example I know of creating ad-hoc
> packages outside the ports, is by Dag-Erling:
> 
> https://blog.des.no/2013/08/creating-pkgng-packages-without-ports/
> https://blog.des.no/2013/08/pkgng-without-ports-addenda/

Thanks, that was helpful