The Media Transfer Protocol (MTP) is an extension to the Picture Transfer Protocol (PTP) communications protocol that allows media files to be transferred automatically to and from portable devices. Whereas PTP was designed for downloading photographs from digital cameras, Media Transfer Protocol allows 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. MTP is a key part of WMDRM10-PD, a digital rights management (DRM) service for the Windows Media platform. In 2011, it became the standard method to transfer files to and from Android. MTP is part of the "Windows Media" framework and thus closely related to Windows Media Player. Versions of the Microsoft Windows operating system from Windows XP SP2 support MTP. Windows XP requires Windows Media Player 10 or higher; later Windows versions have built-in support. Microsoft has made an MTP Porting Kit available for older versions of Windows back to Windows 98. The USB Implementers Forum device working group standardized MTP as a full-fledged Universal Serial Bus (USB) device class in May 2008. Since then MTP is an official extension to PTP and shares the same class code. Overview The main purpose of this protocol is to allow only the transfer of media files and associated metadata to and from portable devices, one transfer function, in or out, at a time. It does not support operations such as open, edit and modify. A workaround is to copy to the hosting system for these operations and then copy back. A battery-powered mobile device can report its battery charge level through MTP. The protocol was originally implemented for use across USB but extended for use across TCP/IP and Bluetooth. Windows Vista supports MTP over TCP/IP. Windows 7 and Windows Vista with the Platform Update for Windows Vista also support MTP over Bluetooth. The host connecting to an MTP device is called an MTP Initiator whereas the device itself is an MTP Responder. A main reason for using MTP rather than, for example, the USB mass-storage device class (MSC) is that the latter operates at the level of mass storage device blocks, rather than at the level of files, or blocks within files, in a file system. In other words, the USB mass storage class is designed to give a host computer undifferentiated access to bulk mass storage, such as compact flash, rather than