Permission

A permission is a kind of access:

"A particular form of allowed access, e.g., permission to READ as contrasted with permission to WRITE. " (1)

In Zope, permissions are extensible. Objects don't just have read/write/execute permissions.

Extensible permissions are both a blessing and a curse. Zope's permissions are, perhaps, too easy to define. In Zope 2, there are too many permissions, making effective security management difficult. Zope 3 will attempt to solve this problem in a number of ways:

We'll give more careful thought to the standard permissions and the way new permissions are identified based on experience from Zope 2.
We'll provide the ability to organize permissions into categories. (We need proposals for how to do this.) A site manager can, if they choose, make permission settings for categories, rather than individual permissions.
We'll put permission definition in the hands of the site manager, making it relatively straightforward for them to design permission schemes that are right for them.

(1): Jerome H. Saltzer, and Michael D. Schroeder. The Protection of Information in Computer Systems. (invited tutorial paper) Proceedings of the IEEE 63, 9 (September 1975) pages 1278-1308. http://web.mit.edu/Saltzer/www/publications/protection/index.html