anchor.diff:  
   #### PHP\_EXTENSIONS vs. ZEND\_EXTENSIONS
   
  -PHP has two kinds of extensions, "PHP extensions" and "Zend extensions". These [hook into the PHP executable in different ways](https://wiki.php.net/internals/extensions).
  +PHP has two kinds of extensions, _PHP extensions_ and _Zend extensions_. These hook into the PHP executable in different ways. See [https://wiki.php.net/internals/extensions](https://wiki.php.net/internals/extensions) for more information about the way extensions work internally in the engine.
   
  -For this reason, they are specified differently in ini files. Your app will fail if a Zend Extension is specified as a PHP Extension, or vice versa.
  +Because they hook into the PHP executable in different ways, they are specified differently in ini files. Apps fail if a Zend extension is specified as a PHP extension, or a PHP extension is specified as a Zend extension.
   
  -If you see this error:
  +If you see the following error, move the `example` extension from `extension` to `zend_extension`, then re-push your app:
   
   ```
   php-fpm | [warn-ioncube] The example Loader is a Zend-Engine extension and not a module (pid 40)
  
positive.code: 
  #### <a id="php_ini_d"></a> .bp-config/php/php.ini.d/
  
  The buildpack will add any `.bp-config/php/php.ini.d/<file>.ini` files it finds in the application to the PHP configuration. This can be used to change any value which is acceptable to php.ini [(list of directives)](http://php.net/manual/en/ini.list.php).
  
  For example adding a file `.bp-config/php/php.ini.d/something.ini` to your app, with contents
  
  ```
  default_charset="UTF-8"
  default_mimetype="text/xhtml"
  ```
  
  would override both the default charset and mimetype.
  
  ##### Precedence
  
  In order of highest precedence, php config values come from.
  
  * php scripts using ini_set() to manually override config files
  * user.ini files (for local values)
  * .bp-config/php/php.ini.d overrides master value but, local value is still the one from user.ini
  
  #### <a id="fpm_d"></a> .bp-config/php/fpm.d/
  
  The buildpack will add any `.bp-config/php/fpm.d` files it finds in the application to the PHP-FPM configuration. This can bes used to change any value which is acceptable to `php-fpm.ini` [(list of directives)](http://php.net/manual/en/install.fpm.configuration.php)
  
  ### <a id="php-extensions"></a> PHP Extensions
  
  The buildpack will add any `.bp-config/php/php.ini.d/<file>.ini` files it finds in the application to the PHP configuration. This can be used to enable PHP or ZEND extensions. For example,
  
  
  ```
  
negative.code: php-fpm | NOTICE: PHP message: PHP Fatal error:  Unable to start example Loader module in Unknown on line 0
  ```
  
  If you see the following error, move the `example` extension from `zend_extension` to `extension`, then re-push your app.
  
  ```
  NOTICE: PHP message: PHP Warning: example MUST be loaded as a Zend extension in Unknown on line 0
  ```
  
  ### <a id="php-modules"></a> PHP Modules
  
  You can include the following modules by adding them to the `PHP_MODULES` list:
  
    - `cli`, installs `php` and `phar`
    - `fpm`, installs `PHP-FPM`
    - `cgi`, installs `php-cgi`
    - `pear`, installs Pear
  
  By default, the buildpack installs the `cli` module when you push a standalone app, and installs the `fpm` module when you push a web app. You must specify `cgi` and `pear` if you want them installed.
  
  ## <a id="buildpack-extensions"></a>Buildpack Extensions
  
  The buildpack comes with extensions for its default behavior. These are the [HTTPD], [Nginx], [PHP], and [NewRelic] extensions.
  
  The buildpack is designed with an extension mechanism, allowing app developers to add behavior to the buildpack without modifying the buildpack code.
  
  When you push an app, the buildpack runs any extensions found in the `.extensions` directory of your app.
  
  The [Developer Documentation](https://github.com/cloudfoundry/php-buildpack/blob/master/README.md) explains how to write extensions.
  
  