UNC/LFN Support

Required:
Your application must support the Universal Naming Convention (UNC). UNC paths allow logical connections to network devices without the need to specifically reference a network drive letter. Your application does not need to be network-aware per se, but it does need to work seamlessly in a network environment. The system must be able to locate the network server and path with the UNC name even over a modem connection. Supporting UNC does not mean that the application is disallowed from presenting network drive letters to users. It merely means that the user must have the option of using only the UNC path name.

NOTE    An LFN is 260 characters, which in general includes 3 bytes for "<driveletter>:\", 255 bytes for the filename+extension, and 2 bytes for the null terminator. A UNC path has 2 bytes for "\\" instead of 3 bytes for "<driveletter>:\", and the path may not include an extension (filetype).

Required:
If your application saves files that are exposed to the user, your application must support LFNs with all of the following required features:

• Users must be able to enter names of 255 characters, including all uppercase and lowercase standard characters, embedded spaces, embedded periods, etc.
  
  
• Leading and trailing spaces must be stripped by the Save As command. To test this, enter a name with leading and trailing spaces, such as “####This is a test###”, retrieve the file, and then make sure the spaces are deleted.

NOTE    Here and throughout this handbook, the number sign (#) indicates a spacebar space.

• Question marks anywhere in the file name must prevent the file from being saved. No error message needs to be displayed.
  
  
• The characters within the quotation marks “ + , ; = [ ] ” must be supported anywhere in the name, including leading and trailing. These should not cause any error conditions. (NOTE    support for leading and trailing periods has been dropped from the Logo requirements.)

Required:
If a file name is fully exposed in Windows Explorer, it must be a fully supported LFN. Applications are allowed to use “labeling schemes” in which a user is saving, for example, a report type or a game state, without actually creating a file that is exposed to the user in Windows Explorer.

Required:
The application must use LFNs for displaying all documents and data files in the shell, in title bars, in dialog boxes and controls, and with icons.

Required:
You must test your LFN functionality on Windows NT FAT, NTFS, and compressed NTFS partitions.