caching question

[silver*]

Hello, I would just like to confirm my understanding of all the different types of caching in web applications  I am assuming that a php accelerator such as PHPA, smarty template engine and memcached for the database are being used. If a page is requested, PHPA is checked first to see if the page is in the op-code cache. If it is not there, smarty's cache is checked to see if there is a cached version of the script. Finally, if there is no script in smarty's cache, memcached for the database may be used if certain queries are needed. Thanks.