On Wed, 22 Feb 2017 07:10:25 +0100 Ulrich Mueller wrote:
> >>>>> On Tue, 21 Feb 2017, Gordon Pettey wrote:
> 
> > There is no requirement for category names to be x-y.
> 
> https://projects.gentoo.org/pms/6/pms.html#x1-180003.1.1 "Category Names"

I don't see a requirement here, only note on most common pattern:

``Note: A hyphen is not required because of the virtual category.
Usually, however, category names will contain a hyphen.''

So "printing" sounds good. Prefix will not give users any useful
information anyway in this case.

Best regards,
Andrew Savchenko