Joomla Article add custom Options

I am trying to add extra fields to the Backend page of Joomla-Articles. Because I want to use them in my layout override. Therefore I tried to change parameters in:

/html/components/com_content/views/article/tmpl/default.xml

Now my questions:

1. Why are there no changes visible, when changing anything in this file?
2. Is it possible to overrite this xml-file with an Joomla layout-overwrite in m开发者_JAVA技巧y Template?
3. I only want to display this fields to Articles of an custom category. Is this possible? (Maybe via extended layout overwrite?)

Thanks for your help guys, Ripei

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The parameters in that XML files only determine the parameters that are displayed in the menu item associated with the relate view. In order to add additional fields to articles you are going to either hack the core or use a CCK type extension. Unfortunately, I don't think any of the CCK extensions have been release for 1.6 yet. I know several are in the works and jSeblod 2.0 for Joomla 1.6 was supposed to be released last week but doesn't appear to be available yet.

http://www.jseblod-cck.com/