General I/O targets do not support special, device-specific data formats, such as USB request blocks. Before drivers send data to a general I/O target, they must put data into a write buffer in a format that the I/O target can interpret. Likewise, when drivers read data from a general I/O target, the drivers must be able to interpret the contents of data buffers that they receive from the target.

The following general I/O targets are currently supported by UMDF:

• The default I/O target (the next-lower driver in the device stack)
• A file-handle-based I/O target for a different sub-system

The following sections describe how to initialize and use a general I/O target: