quick question. Can ALL files use template override?

I don't want to edit core files, but the override guide says it only works where 'custom' already exists

Custom is the folder that you create.

Take a look at the tutorial in the help section of this site. It explains it better than the guide that comes with it.

you create the template folder, and call it something you'll recognize. for me, I called the the name of the store.

There are several files and folders that you will need to create in order to make the template override system work properly.

the guide is correct, the other sections of zen (the admin tree among others) are not set up to test for an overide condition. I just make a backup folder with the originals in it. before doing any upgrading I can see what files I've played with and make any adjustments (file compares) from there

Quick answer: no. :)

Don't look for "custom" - look for "classic." The "custom" folder is the one you will create.
Here's a list from 1.3.7:

./includes/languages/english/classic
./includes/languages/english/html_includes/classic
./includes/languages/english/extra_definitions/classic
./includes/languages/english/modules/order_total/classic
./includes/languages/english/modules/payment/classic
./includes/languages/english/modules/shipping/classic
./includes/languages/classic
./includes/modules/classic
./includes/modules/sideboxes/classic
./includes/templates/classic

Scott

Here is an Overrides Chart which may be of benefit:
http://www.zen-cart.com/index.php?main_page=product_contrib_info&cPath=40_47&products_id=298

Thanks.

Yes, I got confused between custom and classic, but I do understand how it works.
It was the confusion between the advice not to edit certain files, and the fact that classic folders don't exist everywhere that confused me.

Cheers