max-uncheck

(Optional) is the maximum time in seconds allowed between consecutive up-to-date checks. If set to 0 (default), a check is made every time the document is accessed, and the lm-factor has no effect.

lm-factor

(optional)A floating-point number representing the factor used in estimating expiration time, which is how long a document might be up to date based on the time it was last modified. The time elapsed since the last modification is multiplied by this factor. The result gives the estimated time the document is likely to remain unchanged. Specifying a value of 0 turns off this function. The caching system then uses only explicit expiration information which is rarely available. Only explicit Expires HTTP headers are used. This value has no effect if max-uncheck is set to 0.

connect-mode

Specifies network connectivity and can be set to these values: 

• always (default) connects to remote servers when necessary.

• fast-demo connects only if the item isn’t found in the cache.

• never no connection to a remote server is ever made; returns an error if the document is not found in the cache.

cover-errors

If present and greater than 0, returns a document from the cache if the remote server is down and an up-to-date check cannot be made. The value specified is the maximum number of seconds since the last up-to-date check; if more time has elapsed, an error is returned. Using this feature involves the risk of getting stale data from the cache while the remote server is down. Setting this value to 0, or not specifying it (default) causes an error to be returned if the remote server is unavailable. 

term-percent

Indicates that the server should keep retrieving data if more than the specified percentage of the document has already been retrieved.