According to the standard, Pragma is implementation dependent (section 14.32), except for no-cache because of its wide use. Cache-Control (section 14.9) is the proper way to control caching. This is what the standard says for a Cache-Control: public:
Indicates that the response MAY be
cached by any cache, even if it would
normally be non-cacheable or cacheable
only within a non- shared cache.