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where <cache root> is a folder whose location is configurable during client installation and whose default is within the user's home directory; <hash prefix> is the first three two hex digits of the hash, and <hash> is the name used for the file, the full MD5 checksum. The reason for using the intermediate <hash prefix> directory is to avoid having too many files in a single folder. (TODO: Alternative is to make <hash> a folder and place the file inside, with the original file name. If so, the file name must be disregarded by the client.)
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