15.1 DOS-internals and programming aspects 353 15.2 History of the AmigaDOS filesystem 354 15.3 Block types used in the filesystem hierarchy 355 15.3.1 General remarks on the block structure 355 15.3.2 Strings in names and comments 355 15.3.3 The root block 356 15.3.3.1 Block types, T_SHORT, ST_ROOT 356 15.3.3.2 Size of the hash table 356 15.3.3.3 Checksum 356 15.3.3.4 Bitmap status 358 15.3.3.5 Pointers, bitmap, and the MountList 358 15.3.3.6 Pointer to the bitmap extension 358 15.3.3.7 Different types of dates 358 15.3.3.8 Volume name 359 15.3.4 Directories and common attributes 359 15.3.4.1 ST_USERDIR block 360 15.3.4.2 Pointer to own T_SHORT block 360 15.3.4.3 Arrangement of the contents of directories 360 15.3.4.4 Flags 363 15.3.4.5 Comment 364 15.3.4.6 Name 364 15.3.4.7 Link chain 364 15.3.4.8 Hash chain 364 15.3.4.9 Parent directory 364 15.3.5 Files and their components 364 15.3.5.1 File headers 364 15.3.5.2 The supplement: extension blocks 366 15.3.5.3 Data blocks of the old filesystem 367 15.3.5.4 Data blocks of the FastFileSystem 368 15.3.6 Turning a tree into a graph: links 369 15.3.6.1 Hard links 369 15.3.6.2 Soft links 369 15.3.7 The bitmap 369 15.3.7.1 Checksum 369 15.3.7.2 Bit by bit 369 15.3.8 The bitmap extension 373 15.3.9 Reserved blocks and boot blocks 373 15.4 An overview of all block types 374