Removed Extensions
New Classes
Migrating from PHP 5.1.x to PHP 5.2.x
PHP Manual

## New Extensions

The following are new extensions added (by default) as of PHP 5.2.0:

- Filter - validates and filters data, and is designed for use with insecure data such as user input. This extension is enabled by default; the default mode RAW does not impact input data in any way.
- JSON - implements the JavaScript Object Notation (JSON) data interchange format. This extension is enabled by default.
- Zip - enables you to transparently read or write ZIP compressed archives and the files inside them.