concerning the non-free status of ngspice

[budomaru]

Hi, I noticed that ngspice (as well as tclspice) is in the non-free
section of the repositories. I downloaded ngspice23 and it doesn't seem
at all incompatible with the Debian definition of free software, unless
the fact that its essentially under multiple free software licenses or
that part of it is under the public domain hurts its status as free
software.

I would like to know why it's in that section. It seems perfectly free
as software to me and if its inclusion in the non-free section is
intentional, I'd like to know the reason so that I don't reject software
simply because it's in that part of the repositories (when it complies
with my personal requirements for being free).

Thankyou