Event Observer

<config>
  <frontend> [1]
    <events>
      <catalog_product_load_after> [2]
      <observers>
        <yourModule> [3]
          <type>singleton</type> [4]
            <class>module/observer</class> [5]
          <method>catalogProductLoadAfter</method> [6]
        </yourModule>
      </observers>
      </catalog_product_load_after>
    </events>
  </frontend>
</config>

[1] Area: adminhtml,frontend,oder,global
[2] Event Code
[3] Must be unique within the event observer.
[4] "model" or "singleton"
[5] Your_Class_Name oder module/class
[6] The method to be called on the observer instance.

Rewrite Controllers

<config>
  <frontend> [1]
    <routers>
      <checkout> [2]
        <args>
          <modules>
            <yourModule
          before="Mage_Checkout">Namespace_Module_Overwrite_Checkout</yourModule> [3]
          </modules>
        </args>
      </checkout>
    </routers>
  </frontend>
</config>

[1] Depending on the controllers area "frontend" or "admin"
[2] Router node of the module to be overridden (look it up in the config.xml of that module)
[3] The tag <yourModule> can be anything,it must be unique within the <modules> node.
Your_Module_Overwrite_Checkout (is mapped to directory)
Your/Module/controllers/Overwrite/Checkout/

Register Module Controllers

<config>
  <frontend> [1]
    <routers>
      <yourModule> [2]
        <use>standard</use> [3]
        <args>
          <module>Namespace_Module</module> [4]
          <frontName>yourmod</frontName> [5]
        </args>
      </yourModule>
    </routers>
  </frontend>
</config>

[1] Depending on the controllers area "frontend" or "admin"
[2] Must be unique
[3] "admin" for Adminhtml controllers,otherwise "standard"
[4] Namespace and Name of the Module as defined in the <config><modules> node
[5] The URL part to point to the controller directory (e.g. http://example.com/yourmod)
Magento will look in Namespace/Module/controllers/ for the called controller.

Rewrite a Model/Block/Helper

<config>
  <global>
    <models|block|helper> [1]
      <!-- 被重写module的简称(shorthand) -->
      <sales> [2]
        <rewrite>
          <!-- 被重写类的后缀名 -->
          <order_item>Namespace_Module_Model_Sales_Order_Item</order_item> [3]
        </rewrite>
      </sales>
    </models|block|helper>
  </global>
</config>

[1] Depending on object type "models","helpers" or "blocks"
[2] Modul shorthand
[3] The tag is the class to override,the content is the full name of the replacement class.

Define a Model / Block / Helper module shorthand

<config>
    <global>
        <models> [1]
            <(shorthand)> [2]
                <class>Namespace_Module_Model</class> [3]
            </(shorthand)>
        </models>
        <blocks>
            <(shorthand)>
                <class>(ClassName_Prefix)</class>
            </(shorthand)>
        </blocks>
        <helpers>
            <(shorthand)>
                <class>(ClassName_Prefix)</class>
            </(shorthand)>
        </helpers>
    </global>
</config>

[1] Depending on object type "models","helpers" or "blocks"
[2] The module shorthand,must be unique for the module
[3] Classname prefix,will replace the shorthand [2] when resolving a class name.

depends

<config>
    <modules>
         <(NameSpace_ModuleName)>
             <active>[true|false]</active>
             <codePool>[core|community|local]</codePool>
             <depends>
                 <(AnotherNameSpace_ModuleName) />
             </depends>
             <version>(version_number)</version>
         </(NameSpace_ModuleName>
    </modules>
</config>

models

<global>
    <models>
        <(modulename)>
            <class>(ClassName_Prefix)</class>
            <resourceModel>(modulename)_(resource_model_type)</resourceModel>
            <(modulename)_(resource_model_type)>
                <!-- definition -->
            </(modulename)_(resource_model_type)>
            <rewrite><!-- definition --></rewrite>
        </(modulename)>
    </models>
    <resources>
        <(modulename)_setup><!-- definition --></(modulename)_setup>
        <(modulename)_read><!-- definition --></(modulename)_read>
        <(modulename)_write><!-- definition --></(modulename)_write>
    </resources>
</global>

Setup Resource

<global>
    <!-- ... -->
    <resources>
        <weblog_setup>
            <setup>
                <module>Magentotutorial_Weblog</module>
                <class>Magentotutorial_Weblog_Model_Resource_Setup</class>
            </setup>
        </weblog_setup>
    </resources>
    <!-- ... -->
</global>

fieldsets

<global>
    <fieldsets>
        <(page_handle?)>
            <(field_name)>?</(field_name)>
        </(page_handle?)>
    </fieldsets>
</global>

template

<global>
    <template>
        <email>
            <(email_template_name)
                module="(modulename)"
                translate="[label][,description]"
                >
                <!-- definition -->
            <(/email_template_name)>
        </email>
    </template>
</global>

events

<global>
    <events>
        <(event_name)>
            <observers>
                <class>log/visitor</class>
                <method>bindCustomerLogin</method>
            </observers>
        </(event_name)>
    </events>
</global>

cronjob

<config>
    <crontab>
        <jobs>
            <NameSpace_ModuleName>
                <schedule>
                    <cron_expr>*/6 * * * *</cron_expr>
                </schedule>
                <run>
                    <model>NameSpace/ModuleName::cron</model>
                </run>
            </NameSpace_ModuleName>
        </jobs>
    </crontab>
</config>

Layout

<!-- default是一个handle，即在所有页面生效 -->
<default>
    <block type="page/html_head" name="head" as="head">
        <!-- add js -->
        <action method="addJs"><script>prototype/prototype.js</script></action>
        <!-- add css -->
        <action method="addCss"><stylesheet>css/styles.css</stylesheet></action>
    </block>
    <!-- reference是对已存在的block进行替换 -->
    <reference name="left">
        <block type="catalog/product_compare_sidebar" before="cart_sidebar" name="catalog.compare.sidebar" template="catalog/product/compare/sidebar.phtml"/>
    </reference>
</default>
<!-- <[module]_[controller]_[action]> 指定handle的layout -->
<catalog_category_default translate="label">
    <label>Catalog Category (Non-Anchor)</label>
    <reference name="root">
        <!-- action用来调用一个程序方法 -->
        <action method="setTemplate"><template>page/2columns-left.phtml</template></action>
    </reference>
</catalog_category_default>
<catalog_product_index>
    <!-- 将使用与catalog_category_default一样的layout，用于一份layout影响多个页面 -->
    <update handle="catalog_category_default" />
</catelog_product_index>

Layout: block

<!--
"catalog/product_view"的声明方法名为分组类名(Grouped Class Names)
catalog会搜索XML的global/blocks/catalog，默认是Mage_Catalog_Block
product_view补充后缀为Mage_Catalog_Block_Product_View
-->
<block
    type="catalog/product_view" <!-- block的实现代码，决定block中$this的意义 -->
    name="product.info" <!-- name是layout之中被引用时的唯一标识 -->
    as="product-info" <!-- 别名 -->
    template="catalog/product/view.phtml" <!-- 给block套上的template -->
    after="-" <!-- 顺序，代表在XX block之后 -->
    output="toHtml" <!--声明用于呈现到页面上的处理函数，toHtml是默认值 -->
/>

EAV

<global>
    <eav_attributes><!-- definition --></eav_attributes>
</global>