For a long time Apple has stored structured metadata about files in special files called resource forks . These files tend to pop up in archives that were created or packed on an Apple computer. Typically you can find these files in a directory called __MACOSX : $ file __MACOSX/test/._.DS_Store __MACOSX/test/._.DS_Store: AppleDouble encoded Macintosh file I try to recognize these files, tag them and then ignore them, as the information contained in it is not very useful for me Apple resource fork structure An Apple resource fork file consists of a header and then a number of descriptors of each entry. A full description of the values of descriptors can be found in Appendix A & B of RFC1740 . Apple resource fork header The header consists of: signature: 0x00 0x05 0x16 0x07 version number (4 bytes) filler (16 bytes) - these should all be 0x00 number of entries (2 bytes) - this is in big endian format The minimum resource fork file is 4 + 4 + 16 + 2 = 26 b...