Magento sample shipping carrier configuration for an extension's etc/adminhtml/system.xml: extensibility alpha-1

system.xml

<config>
    <system>
        <section id="carriers">
            <group id="acme" translate="label" module="Acme_Carrier" type="text" sortOrder="100" showInDefault="1" showInWebsite="1" showInStore="1">
                <label>Acme</label>
                <field id="active" translate="label" type="select" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Enabled for Checkout</label>
                    <source_model>Mage_Backend_Model_Config_Source_Yesno</source_model>
                </field>
                <field id="free_shipping_enable" translate="label" type="select" sortOrder="210" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Free Shipping with Minimum Order Amount</label>
                    <source_model>Mage_Backend_Model_Config_Source_Enabledisable</source_model>
                </field>
                <field id="free_shipping_subtotal" translate="label" type="text" sortOrder="220" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Minimum Order Amount for Free Shipping</label>
                    <validate>validate-number validate-zero-or-greater</validate>
                </field>
                <field id="handling_type" translate="label" type="select" sortOrder="110" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Calculate Handling Fee</label>
                    <source_model>Mage_Shipping_Model_Source_HandlingType</source_model>
                </field>
                <field id="handling_action" translate="label" type="select" sortOrder="120" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Handling Applied</label>
                    <source_model>Mage_Shipping_Model_Source_HandlingAction</source_model>
                </field>
                <field id="handling_fee" translate="label" type="text" sortOrder="130" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Handling Fee</label>
                    <validate>validate-number validate-zero-or-greater</validate>
                </field>
                <field id="max_package_weight" translate="label" type="text" sortOrder="80" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Maximum Package Weight (Please consult your shipping carrier for maximum supported shipping weight)</label>
                    <validate>validate-number validate-zero-or-greater</validate>
                </field>
                <field id="min_package_weight" translate="label" type="text" sortOrder="90" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Minimum Package Weight (Please consult your shipping carrier for minimum supported shipping weight)</label>
                    <validate>validate-number validate-zero-or-greater</validate>
                </field>
                <field id="sort_order" translate="label" type="text" sortOrder="1000" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Sort Order</label>
                </field>
                <field id="sallowspecific" translate="label" type="select" sortOrder="900" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Ship to Applicable Countries</label>
                    <frontend_class>shipping-applicable-country</frontend_class>
                    <source_model>Mage_Shipping_Model_Config_Source_Allspecificcountries</source_model>
                </field>
                <field id="specificcountry" translate="label" type="multiselect" sortOrder="910" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Ship to Specific Countries</label>
                    <source_model>Mage_Directory_Model_Config_Source_Country</source_model>
                    <can_be_empty>1</can_be_empty>
                </field>
                <field id="showmethod" translate="label" type="select" sortOrder="920" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Show Method if Not Applicable</label>
                    <frontend_class>shipping-skip-hide</frontend_class>
                    <source_model>Mage_Backend_Model_Config_Source_Yesno</source_model>
                </field>
                <field id="specificerrmsg" translate="label" type="textarea" sortOrder="800" showInDefault="1" showInWebsite="1" showInStore="1">
                    <label>Displayed Error Message</label>
                </field>
                <field id="debug" translate="label" type="select" sortOrder="920" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Debug</label>
                    <source_model>Mage_Backend_Model_Config_Source_Yesno</source_model>
                </field>
            </group>
        </section>
    </system>
</config>