PHP

This sets the maximum amount of memory in bytes that a script is allowed to allocate. This helps prevent poorly written scripts for eating up all available memory on a server. Note that to have no memory limit set this directive to -1.Prior to PHP 5.2.1 in order to use this directive it had to be enabled at compile time by using --enable-memory-limit in the configure line. This was also required to define the functions memory_get_usage() and memory_get_peak_usage(). When an integer is used the value is measured in bytes

Enable compatibility mode with Zend Engine 1 (PHP 4). It affects the cloning casting (objects with no properties cast to FALSE or 0) and comparing of objects. In this mode objects are passed by value instead of reference by default.

Determines the size of the realpath cache to be used by PHP. This value should be increased on systems where PHP opens many files to reflect the quantity of the file operations performed.

The number of significant digits displayed in floating point numbers.

Whether to warn when arguments are passed by reference at function call time. This method is deprecated and is likely to be unsupported in future versions of PHP Zend. The encouraged method of specifying which arguments should be passed by reference is in the function declaration. You're encouraged to try and turn this option Off and make sure your scripts work properly with it in order to ensure they will work with future versions of the language (you will receive a warning each time you use this feature). Passing arguments by reference at function call time was deprecated for code cleanliness reason. Function can modify its argument in undocumented way if it didn't declared that the argument is passed by reference. To prevent side-effects it's better to specify which arguments are passed by reference in function declaration only.

Enables the use of ASP-like % % tags in addition to the usual ?php ? tags. This includes the variable-value printing shorthand of %= $value % . For more information see Escaping from HTML. Note: Support for ASP-style tags was added in 3.0.4.

Enforce year 2000 compliance (will cause problems with non-compliant browsers)

Decides whether PHP may expose the fact that it is installed on the server (e.g. by adding its signature to the Web server header). It is no security threat in any way but it makes it possible to determine whether you use PHP on your server or not.

Tells whether the short form ( ? ? ) of PHP's open tag should be allowed. If you want to use PHP in combination with XML you can disable this option in order to use ?xml ? inline. Otherwise you can print it with PHP for example: ?php echo ' ?xml version=1.0'; ? . Also if disabled you must use the long form of the PHP open tag ( ?php ? ). Note: This directive also affects the shorthand ?= which is identical to ? echo. Use of this shortcut requires short_open_tag to be on.

Enable the Asynchronic send mode