How can we edit config.xml file of a core module?

Question

For example, I would like to edit app/code/core/Enterprise/Rma/etc/config.xml,I copied config.xml file to local/Enterprise/Rma/etc/config.xml and made changes but it didn't work.

I don't want to make any other changes to any other files of RMA module.

Answer 1

You have to create a new module under local : Yourcompany_Rma

In this module, define a minimalist etc/config.xml with the XML rewrite you need :

<config>
    <modules>
        <Yourcompany_Rma>
            <version>0.1.0.0</version>
        </Yourcompany_Rma>
    </modules>
    <global>
        <payment>
            <cc>
                <types>
                    <AE>
                        <code>AE</code>
                        <name>American Express</name>
                        <order>0</order>
                    </AE> [...]

And then in the app/etc/modules folder, add a new Yourcompany_Rma.xml (or Yourcompany_All.xml) with :

<config>
    <modules>
        <Yourcompany_Rma>
            <active>true</active>
            <codePool>local</codePool>
            <depends>
                <Enterprise_Rma/>
            </depends>
        </Yourcompany_Rma>
    </modules>
</config>

The depends node is vital because it will tell magento to load your XML after magento's one in order to your rewrite to work