The Media Transfer Protocol is a devised set of custom extensions to the Picture Transfer Protocol (PTP). Whereas PTP was designed for downloading photographs from digital cameras, Media Transfer Protocol supports the transfer of music files on digital audio players and media files on portable media players, as well as personal information on personal digital assistants. Media Transfer Protocol (commonly referred to as MTP) is part of the "Windows Media" framework and thus closely related to Windows Media Player. Windows Vista has built-in support for MTP. Support for Media Transfer Protocol in Windows XP requires the installation of Windows Media Player 10 or higher. Mac and Linux systems have software packages to support it. The USB Implementers Forum device working group standardized MTP as a fully fledged Universal Serial Bus (USB) device class in May 2008. MTP is since then, an official extension to PTP and shares the same class code.