PHP supports the direct io functions as described in the Posix Standard (Section 6) for performing I/O functions at a lower level than the C-Language stream I/O functions (fopen(), fread(),..). The use of the DIO functions should be considered only when direct control of a device is needed. In all other cases, the standard filesystem functions are more than adequate.
This extension has been moved to the » PECL repository and is no longer bundled with PHP as of PHP 5.1.0.
This extension is only available on Windows Platforms as of PHP 5.0.0