question about ELF executable

Hi all, Is there perhaps anyone here that can answer this question? ELF executables have program segment headers, containing a field p_offset that should refer to the offset in the file where the section of data starts. However, regardless what executable I look at, they all seem to contain a header that contains a p_offset = 0. This would mean the absolute start of the file, exactly where the ELF header itself is located. For example, when I do: $ readelf -a /bin/bash |less I get: Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align PHDR 0x000034 0x08048034 0x08048034 0x000e0 0x000e0 R E 0x4 INTERP 0x000114 0x08048114 0x08048114 0x00013 0x00013 R 0x1 [Requesting program interpreter: /lib/ld-linux.so.2] LOAD 0x000000 0x08048000 0x08048000 0x837bc 0x837bc R E 0x1000 LOAD 0x084000 0x080cc000 0x080cc000 0x05350 0x09a94 RW 0x1000 DYNAMIC 0x088fa4 0x080d0fa4 0x080d0fa4 0x000d8 0x000d8 RW 0x4 NOTE 0x000128 0x08048128 0x08048128 0x00020 0x00020 R 0x4 GNU_EH_FRAME 0x083790 0x080cb790 0x080cb790 0x0002c 0x0002c R 0x4 The 3rd header contains an p_offset=0. Why? I don't get it. Bert