Magento defines its shipping methods, also called carriers, under the
config/default/carriers XML element.
If you take a look at
app/code/core/Mage/Shipping/etc/config.xml, you can see several carriers' definition as the one for the Flat Rate shipping method, as the following code:
<?xml version="1.0"?> <config> <!-- ... --> <default> <carriers> <flatrate> <active>1</active> <sallowspecific>0</sallowspecific> <model>shipping/carrier_flatrate</model> <name>Fixed</name> <price>5.00</price> <title>Flat Rate</title> <type>I</type> <specificerrmsg>This shipping method is currently unavailable. If you would like to ship using this shipping method, please contact us.</specificerrmsg> <handling_type>F</handling_type> ...