PHP comes with many built-in wrappers for various URL-style protocols for use with the filesystem functions such as fopen() and copy(). In addition to these wrappers, you can as of PHP 4.3.0, write your own wrappers using the stream_wrapper_register() function.
Note: The URL syntax used to describe a wrapper only supports the scheme://... syntax. scheme:/ and scheme: syntaxes are not supported.
List of context options is available in the chapter Context options and parameters.