I've wondered this for years and now that I'm customizing (yet another) zen cart installation, I figured I'd ask...

It seems that some files you can place just the defines you want to change in the override file. For example

/inculdes/languages/english.php is overrided with /includes/languages/YOUR_TEMPLATE/english.php and you can pick and choose which defines you include in the new file. Any that you don't, will (logically) be taken from the main file.

BUT this isn't always the case. Other language files you have to include the whole text with all the define or they don't work.

Why is that? Is there any rhyme or reason to it that I'm missing?

- Steven