This Variable set to 0, Disables caching of pages that contain @function formulas. One can also use The field options: $CacheOptions and . $CacheValid in R5 to have the HTTP task cache information for the formulae.
This Variable allows the HTTP engine to more intelligently decide if an HTML page should be cached or not. After looking at the formulae on a page that is being served the engine will decide if the page can be cached for future requests. This can lead to much better performance.
The field options $CacheOptions and $CacheValid appear not to be supported in ND6.