Device driver function 0Fh      Removable Media         b

    Removable Media specifies whether a drive contains a removable
    medium.

    This function is used for block device drivers only.

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    DOS calls this function only if bit 11 is set in the dhAttributes
    field of the DeviceHeader structure for the driver.

    Since DOS assumes this function is always successful, it ignores
    any error value the function returns.

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    rmrUnit
    Specifies the device to check for removable media.

    
    rmrStatus
    Specifies the status of the completed function. If the function
    was successful, the driver must set the done bit (bit 8).
    Otherwise, the driver must set both the error and done bits (bits
    15 and 8) and copy an error value to the low-order byte.