## Physical Device Driver Reference

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### Name or Units

Contains the 8-character name of a character device supported by the character device driver or the number of units supported by the block device driver.

For a character device driver, the name of the device must be uppercase ASCII characters and left-justified with the remaining spaces set to blanks . The device name is used by applications to identify the device for I/O. A character device driver should consider the following rule when selecting a physical device driver name. To avoid conflicts with file names, a character device driver should choose a character string with some unusual character (such as a $ sign) as the last character.

A device name takes precedence over a file name in a DosOpen function. This means that files cannot have the same name as a character device. The DosOpen function always opens the device, rather than the file.