Default client cache time to live. Provides a default expiration interval in case a particular catalog record does not contain a valid catalog::Expiration or vignette::Expiration value, or if a vignette file or material file is accessed directly, rather than via a catalog record.
Real number, 0 or greater. Number of hours until expiration since the reply data was generated. Set to 0 to always expire the reply image immediately, which effectively disables client caching. Set to -1 to mark as never expire.
Inherited from default::Expiration if not defined or if empty.