Percentage of the maximum Time-To-Live of text objects used to
calculate the minimum age that a text object must be before
an up-to-date check is performed with the server as a result
of an IMS request. If the age of a text object is less than
this percentage of the maximum Time-To-Live for text objects,
then an IMS request is served out of the cache.
If zero, an IMS request is always sent to the server.