Magento : Add category attribute

There are following step
1.Create a new module under your local folder, in our case under /app/local/Bd/Customcategoryattribute.
2.Register the module in etc/modules directory Bd_Customcategoryattribute by using the following code

<?xml version="1.0"?>
<config>
  <modules>
    <Bd_Customcategoryattribute>
      <active>true</active>
      <codePool>local</codePool>
      <version>0.1.0</version>
    </Bd_Customcategoryattribute>
  </modules>
</config>
3.Create config.xml under etc directory of your module /app/local/Bd/Customcategoryattribute/etc/config.xml by using the following code

<?xml version="1.0"?>
<config>
  <modules>
    <Bd_Customcategoryattribute>
      <version>0.1.0</version>
    </Bd_Customcategoryattribute>
  </modules>
  <global>
    <helpers>
      <customcategoryattribute>
        <class>Bd_Customcategoryattribute_Helper</class>
      </customcategoryattribute>
    </helpers>
<models>
 <customcategoryattribute>
<class>Bd_Customcategoryattribute_Model</class>
<resourceModel>customcategoryattribute_mysql4</resourceModel>
 </customcategoryattribute>
</models>
<resources>
 <customcategoryattribute_setup>
<setup>
 <module>Bd_Customcategoryattribute</module>
 <class>Mage_Catalog_Model_Resource_Eav_Mysql4_Setup</class>
</setup>
<connection>
 <use>core_setup</use>
</connection>
 </customcategoryattribute_setup>
 <customcategoryattribute_write>
<connection>
 <use>core_write</use>
</connection>
 </customcategoryattribute_write>
 <customcategoryattribute_read>
<connection>
 <use>core_read</use>
</connection>
 </customcategoryattribute_read>
</resources>
  </global>
</config>
4.Create setup file mysql4-install-0.1.0 under sql directory of your module /app/local/Bd/Customcategoryattribute/sql/customcategoryattribute_setup/mysql4-install-0.1.0.php by using the following code

<?php

$installer = $this;

$installer->startSetup();

$installer->addAttribute("catalog_category", "custom_attribute",  array(

    "type"     => "varchar",

    "backend"  => "",

    "frontend" => "",

    "label"    => "Custom Attribute",

    "input"    => "text",

    "class"    => "",

    "source"   => "",

    "global"   => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_STORE,

    "visible"  => true,

    "required" => false,

    "user_defined"  => false,

    "default" => "",

    "searchable" => false,

    "filterable" => false,

    "comparable" => false,

    "visible_on_front"  => false,

    "unique"     => false,

    "note"       => "Extra Attribute"

));

$installer->endSetup();

5. At last create helper Data.php under helper directory of your module /app/local/Bd/Customcategoryattribute/Helper/Data.php by using the following code

<?php class Bd_Customcategoryattribute_Helper_Data extends Mage_Core_Helper_Abstract { }  

Here, 

type:(realted to db)  varchar, text, datetime, int, etc.

input:(reated to frontend filed) text, textarea, date, select, multiselect, select, image

Please comment if u need about other properties. Thanks.