Magento: theme fallback hierarchy question

Can someone verify what I think is what's happening with Magento's fallback theme hierarchy.

1. The final fall-back point is the /base/default/ theme.
2. Within your interface/package (they are the same things right?), your default theme is selected at, from the Magento admin page, System->Configuration->General->Design->Themes->"B" ("B" is an example name of the theme).
3. On top of your defau开发者_如何学Clt package theme, you can select an active theme from System->Design->"A".

So with this setup, Magento will look into "A" first, then in "B", then finally resort to base/default if neither A or B has files it needs.

Correct or no? TIA!

Sorta.

The fall-back hierarchy in Magento CE v1.4+ and EE v1.8+ is as follows.

Look for requested file in:
app/design/frontend/custom_package/custom_theme/
skin/frontend/custom_ package/custom_theme
If not found, look for requested file in:
app/design/frontend/custom_package/default
skin/frontend/custom_package/default
If not found, look for requested file in:
app/design/frontend/base/default
skin/frontend/base/default
If not found, a rendering error will occur.

Source: Magento's Theme Hierarchy - Changes in CEv1.4 and EEv1.8

I will do my best to clarify some points for you.

If you are not using a child theme, magneto will use /base/, however if you have a child theme active, magneto will use your custom theme files.

For example, If your new theme file has a header.phtml file but not footer.phtml, Magento will automatically fall back to the base. this is why its never smart to edit core files