Lester Caine [09-05-20 07.16] :

> I've just found a copy of the FHS rules, and actually it is quite clear
> ... /opt SHOULD be used for additional software and each package should
> be contained in it's own tree below /opt ... FHS simply does not provide
> any rules as to why /usr should be used instead of /opt for additional
> packages over those required by the kernel

that's distro rules
nothing else

all Linux distro says :
use /opt to install software that is not part of the distro

> the package may be totally screwed up
> with respect to a 'standard' FB install - as demonstrated by Fedora

I disagree, it is not "totally screwed up"
you get all under /usr/lib as if it was under /opt

but real files are at their good location
as for example %{_sysconfdir} for conf files

if you build Firebird by yourself, you'd see that the default path is /usr/lib ;)

and again, you have the choice
use distro package, firebird project rpm, firbird project tar.gz, or build it yourself

each of them have its advantage / disadvantage