Changing preferences

[Robert J. Hansen]

Faramir wrote:
>> No, but they may be operating on the assumption their preference list
>> matters.  (Which it very often doesn't; encrypting-to-self and another
>> recipient means there's a 50/50 chance their preference list will be
>> treated as a cap set.  It would appear this ought to be made clear in
>> the docs.)
> 
>   What do you mean? I didn't understand the "cap set" concept, or at
> least, the meaning of these words (I think probably is due my lack of
> vocabulary...).

Imagine a group of people are going to the movies.

"I'd like to see either _Iron Man_, _The Incredible Hulk_, or _The Dark
Knight_."

Compare to:

"I'd like to see _The Incredible Hulk_.  If that's not possible, I'd
like to see _The Dark Knight_.  If neither of them are possible, I'd
like to see _Iron Man_."

The first one says "I'd like to see any of these movies and I don't care
which we choose."  This is a capability set.

The second one says "while I'll watch any of them, I would prefer _The
Incredible Hulk_."  This is a preference list.

In mathematics, a 'set' is usually thought of as a grouping of objects
without regard to order.  A 'list' is usually thought of as a grouping
of objects in a particular order.  This is why we talk about capability
sets and preference lists.

Much of the time, GnuPG will treat key's preference list like a
capability set.