When using the marketing trigger "Current page" with "Customer is viewing a catalog entry".
The template you use is actually saying look for a specific productId on a command called ProductDisplay.
If you look in the dmeletemplate table you could find all the templates for the different triggers and other elements used by marketing.
In this case your interested in the trigger currentCustomerBehaviorProductBrowsing. To see what the rule for the actual trigger you look into behaviorxml.
The standard rule is:
<BehaviorRule command="ProductDisplay" action=""> <Variable name="productId" value="MARKETING_catalogEntryIdList" type="NVP"/> </BehaviorRule>
And as you see in the rule it checks for the command ProductDisplay and the parameter productId and comparing it with catalogEntryIdList which is the list of ids defined in your activity trigger.
In our implementation we had a problem where we needed to trigger the rule on multiple commands because we don't only show products with ProductDisplay. This could be enabled with the use of a comma separated list of commands.
<BehaviorRule command="ProductDisplay,MySpecialProductDisplay" action=""> <Variable name="productId" value="MARKETING_catalogEntryIdList" type="NVP"/> </BehaviorRule>