[Zope] Volatile Properties in ZClasses?

Hi, Take a look at the BannerAd ZClass: (http://www.zope.org/Members/lalo/BannerFolder) Updating the "hits"-property when the banner is loaded, has the effect, that the Banner-Object is backuped by the Zope magic, which is quite annyoing when having a high-traffic site. So, how can one generate volatile properties, which do not get backuped (I tried it whith _hits, but ZClasses do not likte them ;-) --> Zope Error). Is there a reason for not allowing _Variables in ZClasses and how does one solve the Problem in this case (seems like a generael problem) -- Tom Schwaller http://www.linux-magazin.de