Do you know the valid values for http header pragma . I understand no-cache is a however i wnat make it possible for caching what exactly must i place it. Used to do some googleing and all sorts of which i got was most clients ignore this but no information on other values it accepts.

Remarkably there's just one parameter defined automatically, that is no-cache with no new Pragma directives is going to be defined in HTTP according to RFC.

ref: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.32

Furthermore, you will have to make use of the Cache-Control header for controlling the caching actions as opposed to the Pragma directive which appears to become still incorporated simply to offer the legacy HTTP/1..

ref: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9

Bonus: http://www.mnot.net/cache_docs/

You are most likely searching for Cache-Control, this really is supported in HTTP/1.1 and defines more states than Pragma.