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Directories and FilesInformation about individual files is maintained in directories. Each directory entry contains an optional long file name, the short file name (max. 8+3 characters), the date and time of the last file update, the current file size, file attributes, and the first cluster number holding the file's data. Subsequent clusters of the file must be looked up in the FAT. Two types of directories must be distinguished: the root directory and subdirectories. On FAT-12 and FAT-16 drives, the root directory resides in a fixed location immediately following the last copy of the FAT. It has a fixed size determined at format time; its size is recorded in the boot record. The root directory cannot be extended after formatting. Subdirectories are stored like regular files. Unlike the root directory, each subdirectory has a directory entry in its parent directory. This directory entry contains the same information as for files and the space allocated to the subdirectory is recorded in the FAT. Thus, subdirectories can be extended dynamically and their size is not limited. Subdirectories can also be fragmented, just like files. On FAT-32 drives, the root directory is also maintained in a file chain and can thus be extended like any other directory.
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