Martin McClure wrote:

> I do have an image format enhancement I've been considering... and it
> seems now is the time.
>
> Here's a very brief proposal. I can fill in details later, but I want
> let you know right away the basic idea.
>
> I'd like to have a bit in the object header for the purpose of
> marking an object immutable.

Yay! I've always wanted this as well, for exactly the same reasons.
Persistency frameworks are usually brittle in the area of change detection
(I've seen GemStone, Versant and TOPLink, and they all would have benefitted
from this).

Cheers,
Hans-Martin