R.3 Physical Media Interface
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## R.3 Physical Media Interface

These devices may have a wide variety of overall physical characteristics. They shall provide a connector that complies with the USB 1.1 or 2.0 specifications for physical, electrical, signaling, and communications protocol. The electrical signaling and lower level USB protocol support shall comply with the USB 1.1 or 2.0 specifications. The device shall act as a Mass Storage Device, in accordance with the USB Mass Storage Class, as described in the Universal Serial Bus Mass Storage Class, Specification Overview and its subordinate and referenced documents.

### Note

1. The USB base standard and the USB mass storage device standard includes specification for management of device addition and removal, and for negotiation of device command protocol capabilities. Support for these is normally part of the functions provided by the USB Mass Storage driver in an operating system.

2. The USB 2.0 specification specifies 3 speeds of operation, "low-speed", "full-speed" and "high-speed", which are fully interoperable, and this profile does not distinguish between the speeds.

3. The intent is to allow removable 1.1 and 2.0 USB media to interoperate with 1.1 and 2.0 USB devices.

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