<b>{set-max-cache time=seconds}</b>: Set the maximum time this
document can be cached in any ram caches. 

<p>Default is to get this time from the other tags in the document (as
an example, {if supports=...} sets the time to 0 seconds since the
result of the test depends on the client used.

<p> You must do this at the end of the document, since many of the
normal tags will override this value.
