Re: simplest copyleft license for a wiki

[Edmund GRIMLEY EVANS <edmundo@rano.org>]

Henning Makholm <henning@makholm.net>:

> > >    1. You have the right to copy, modify, and/or distribute the work.
> 
> > I don't know what "and/or" means, but I find it hard to imagine a
> > definition of "and/or" which would make this sentence mean that I have
> > clear and explicit permission to distribute modified copies.
> 
> Um, what have you been smoking? That is as clear and explicit as it is
> possible to make it.

I find section 2 of the GPL to be much more clear and explicit.

> "And/or" is a pretty standard way of phrasing an
> inclusive or: You have the right to do one. You have the right to do
> the other.  You have to the right to do both.

The semantics of "or" in English has almost nothing to do with the
"inclusive or" and "exclusive or" of logic. It has more to do with
quantification and has many of the same ambiguities. In general, when
you write "or" you should specify at whose option. For example, in a
contract where ten euros are to be exchanged for "a burger, chips and
cola or lemonade" you'd expect the choice of beverage to be at the
purchaser's option, but grammatically, without further context, it
could mean at the vendor's option.

> If you do both, then,
> naturally, what you distribute is the result of the modifications.

It is possible for me to do both by modifing a program and also
distributing the unmodified program. The best way of giving permission
to distribute modified copies is to say so. "Preparation of
deriviative works" is perhaps even better.

The expression "and/or" is a monstrosity that should be avoided in all
contexts, especially when one is trying to be precise, IMHO.

> Cf. the pine/UW attack which interpreted "right to modify and
> distribute" as: You have the right to modify. You have the right to
> distribute. You *don't* have the right to do both at once.

So, you're saying that "and" on its own doesn't allow both at once. It
must be an XAND :-)

> This is
> exactly what the "and/or" wording seeks to defuse.

But fails absolutely to do so ...