How to create an interstitial banner?

Normally the Interstitial ad is delivered by an ad server. Virtualcms give the chance to create and customize the Interstitial banner.

It can be used to promote an event, such as a week free subscription, or a shipping for free.

The Intersitial ad can:

• contains flash scripts or images;
• set with a count down so that the ad automatically closes when time expires;
• set for appear every "n" views.

It need to have in the code also the follow script:

<script type='text/javascript' src="js/bannerInterstitial.js"></script>