This is a patched version of the RAM Cache Manager from the StandardCacheManagers product. It's single enhancement is the addition of an attribute "maximum_age" that set's a maximum time an object can stay in the cache. After that time an object is expired wether it was changed or not. This is usefull for complex documents that change because of outside events (like complex SQL queries that work on databases that are changed by external programs).
With Zope 2.4 this product is not needed any more, since Zope 2.4 has it's own max_age field on the RAM Cache Manager, as I was told. So this product will be mostly for those of us, who can't always upgrade to the newest Zope as fast as they would like to.