Difference between #4 and #3 of How to customize Yii core messages?

How to customize Yii core messages?
default validation error messages). Customization of these core messages is
needed in two circumstances:

 * When an application is written for non-English users, these core messages
 * Some core messages need to be modified slightly for various reasons. For

messages, you may refer to the article "[How to customize the error message
of a validation rule](/doc/cookbook/1/)".

process with the help of an application component named
"[coreMessages|CApplication::coreMessages]". The component translates
the core message into the [target language|CApplication::language] which is
message will be displayed, instead. 

The idea here is to customize the `coreMessages` component by changing the place
component with the following application configuration:

return array(

the translated messages are located under the directory `protected/messages`.

Next, we need to provide our translations. Under the directory
`protected/messages`, create a subdirectory named `de` which corresponds to the
target language we set in the application configuration. And under the `de`
directory, create a new file named `yii.php`. To this end, we should have the
following directory structure:


Finally, we put message translations in the `yii.php` file. To save time, we may
simply copy the content from `framework/messages/de/yii.php` and modify it as

> Tip: You may wonder why we would take so much trouble in order to customize
the core messages. Why don't we modify the file `framework/messages/de/yii.php`
overwrite your change.

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