Why is Linux the only OS in version identifier list that has a lowercase name?

[Joseph Rushton Wakeling via Digitalmars-d-learn]

On Tuesday, 12 April 2016 at 01:32:02 UTC, Brian Schott wrote:
> On Monday, 11 April 2016 at 23:01:08 UTC, marcpmichel wrote:
>> Is it because Linux is not an OS ? :p
>
> I gnu somebody would bring that up.

There's actually a serious point here, though -- as D is ported 
to other platforms and architectures, it's going to wind up being 
used to target environments that use a Linux kernel but are not 
GNU.  Conversely, there may also be systems that are GNU but not 
Linux (e.g. the recent proposal for an Ubuntu flavour based on 
the FreeBSD kernel).

Are druntime and phobos ready to deal with those kinds of 
eventuality?