Logic Pro 8 "Optimize Files" in Logic Express 7 ?

I'm using Logic Express 7, and I came across a reference to the "Optimize Files" function in the user manual. I'm assuming it would be located somewhere in the Audio Window's local menus, but I can't find it anywhere.

Does anyone know if this function is anywhere to be found in Express, or is it just a feature of Pro? It would be handy to be able to delete the unused portions of audio files, so I could free up more disk space.

Thanks for any help.
its been awhile since ive used 7 or express but look in the audio bin and see if you can "save region as" then once all your audio is edited you can save all the used regions as new audio files.. delete the old regions/audio.. and youll only be left with the smaller edited files.. make sense?.. bit laborious i know
hmm scratch that.. i just went and tried it in L8 and it doesnt reference back to the original region in the arrange.. so youll be lost once you start deleting the large files..
ie.. youll be delteing them form the arrangement page as well....grrrr...let me think some more..