[sorry for the late reply - I was busy and/or traveling the last
couple of days - and I will be afk for almost the next 2 weeks too]

thorpej@wasabisystems.com said:
> Presumably, system firmware would not be using the "NetBSD" VCI. 

_If_ I write a real ROM bootloader for the cesfic one day, I'll
probably use libsa.
This wouldn't be PXE, but see below...

> > Perhaps add a "boot command argument" if given on the
> > bootloader prompt?
> 
> Hm.  Yah, I can see how that would be useful .. but would that be better
> off in the Vendor Encapsulated Options?

In environments where PXE is not available, the "filename" field
or eg some locally defined BOOTP option field could be used for
conditional behaviour.
The strings should look the same as far as possible to avoid
confusion.

best regards
Matthias