Why do invocation codes look different each time they are viewed in the UI?

The “switch_placeholder” defines where an ad will be delivered. A unique sting is populated within this for each instance of every invocation code.

This is so each instance of an ad unit can be identified. If multiple requests are made to the same ad unit on a single page, separate invocation codes, all with a unique string in each set of “switch_placeholder” would be required. This ensures each ad is delivered to the intended instance of the ad unit.