## Physical Device Driver Reference

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### Device-Specific Monitor Information

The character device driver that provides device monitor support must carefully document the following information for its monitors:

The definition of its data streams and their monitor chains. The monitor application developer requires this information for the Index parameter when calling DosMonReg.

The length of its monitor chain buffers. The monitor application developer requires this information so that a large enough private data area can be allocated for the monitor.

The description of its monitor record format, including a detailed description of the flag usage, and expected actions and restrictions of data record consumption. The monitor application developer requires this information to understand the data flowing through the data stream and any actions or responses the physical device driver expects.

A description of conditions under which the physical device driver can block the data stream. The monitor application developer must ensure that the device monitor works with the physical device driver, not against it. The monitor application developer must understand expected blockages in the physical device driver (their causes, their effects) in order to handle them.