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If the filespec begins with a backslash then that sub directory must be directly under the base directory of the filespec (specified on the Define Fileset property page). If you have recursion enabled and a directory by the same name is found elsewhere in the file system but not as a direct subdirectory of the root, then the directory will not be searched. This can be thought of as simply changing the root directory for this pattern.
Example
Using two patterns, only choose files from the directories <root>\DCU\ and <root>\BAK\ even though the root directory may have many more subdirectories:
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