The following are the known types of zipfile extra fields as of thiswriting.  Extra fields are documented in PKWARE's appnote.txt and areintended to allow for backward- and forward-compatible extensions tothe zipfile format.  Multiple extra-field types may be chained together,provided that the total length of all extra-field data is less than 64KB.(In fact, PKWARE requires that the total length of the entire file header,including timestamp, file attributes, filename, comment, extra field, etc.,be no more than 64KB.)Each extra-field type (or subblock) must contain a four-byte header con-sisting of a two-byte header ID and a two-byte length (little-endian) forthe remaining data in the subblock.  If there are additional subblockswithin the extra field, the header for each one will appear immediatelyfollowing the data for the previous subblock (i.e., with no padding foralignment).All integer fields in the descriptions below are in little-endian (Intel)format unless otherwise specified.  Note that "Short" means two bytes,"Long" means four bytes, and "Long-Long" means eight bytes, regardlessof their native sizes.  Unless specifically noted, all integer fields shouldbe interpreted as unsigned (non-negative) numbers.Christian Spieler, 19980918                        -------------------------          Header ID's of 0 thru 31 are reserved for use by PKWARE.          The remaining ID's can be used by third party vendors for          proprietary usage.          The current Header ID mappings defined by PKWARE are:          0x0007        AV Info          0x0009        OS/2 extended attributes      (also Info-ZIP)          0x000a        PKWARE Win95/WinNT FileTimes  [undocumented!]          0x000c        PKWARE VAX/VMS                (also Info-ZIP)          0x000d        PKWARE Unix          0x000f        Patch Descriptor          The Header ID mappings defined by Info-ZIP and third parties are:          0x07c8        Info-ZIP Macintosh (old, J. Lee)          0x2605        ZipIt Macintosh (first version)          0x2705        ZipIt Macintosh v 1.3.5 and newer (w/o full filename)          0x334d        Info-ZIP Macintosh (new, D. Haase's 'Mac3' field )          0x4341        Acorn/SparkFS (David Pilling)          0x4453        Windows NT security descriptor (binary ACL)          0x4704        VM/CMS          0x470f        MVS          0x4b46        FWKCS MD5 (third party, see below)          0x4c41        OS/2 access control list (text ACL)          0x4d49        Info-ZIP VMS (VAX or Alpha)          0x5356        AOS/VS (binary ACL)          0x5455        extended timestamp          0x5855        Info-ZIP Unix (original; also OS/2, NT, etc.)          0x6542        BeOS (BeBox, PowerMac, etc.)          0x756e        ASi Unix          0x7855        Info-ZIP Unix (new)          0xfb4a        SMS/QDOSThe following are detailed descriptions of the known extra-field block types:         -OS/2 Extended Attributes Extra Field:          ====================================          The following is the layout of the OS/2 extended attributes "extra"          block.  (Last Revision 19960922)          Note: all fields stored in Intel low-byte/high-byte order.          Local-header version:          Value         Size            Description          -----         ----            -----------  (OS/2)  0x0009        Short           tag for this extra block type          TSize         Short           total data size for this block          BSize         Long            uncompressed EA data size          CType         Short           compression type          EACRC         Long            CRC value for uncompressed EA data          (var.)        variable        compressed EA data          Central-header version:          Value         Size            Description          -----         ----            -----------  (OS/2)  0x0009        Short           tag for this extra block type          TSize         Short           total data size for this block          BSize         Long            size of uncompressed local EA data          The value of CType is interpreted according to the "compression          method" section above; i.e., 0 for stored, 8 for deflated, etc.          The OS/2 extended attribute structure (FEA2LIST) is compressed and          then stored in its entirety within this structure.  There will only          ever be one block of data in the variable-length field.         -OS/2 Access Control List Extra Field:          ====================================          The following is the layout of the OS/2 ACL extra block.          (Last Revision 19960922)          Local-header version:          Value         Size            Description          -----         ----            -----------  (ACL)   0x4c41        Short           tag for this extra block type          TSize         Short           total data size for this block          BSize         Long            uncompressed ACL data size          CType         Short           compression type          EACRC         Long            CRC value for uncompressed ACL data          (var.)        variable        compressed ACL data          Central-header version:          Value         Size            Description          -----         ----            -----------  (ACL)   0x4c41        Short           tag for this extra block type          TSize         Short           total data size for this block          BSize         Long            size of uncompressed local ACL data          The value of CType is interpreted according to the "compression          method" section above; i.e., 0 for stored, 8 for deflated, etc.          The uncompressed ACL data consist of a text header of the form          "ACL1:%hX,%hd\n", where the first field is the OS/2 ACCINFO acc_attr          member and the second is acc_count, followed by acc_count strings          of the form "%s,%hx\n", where the first field is acl_ugname (user          group name) and the second acl_access.  This block type will be          extended for other operating systems as needed.         -Windows NT Security Descriptor Extra Field:          ==========================================          The following is the layout of the NT Security Descriptor (another          type of ACL) extra block.  (Last Revision 19960922)          Local-header version:          Value         Size            Description          -----         ----            -----------  (SD)    0x4453        Short           tag for this extra block type          TSize         Short           total data size for this block          BSize         Long            uncompressed SD data size          Version       Byte            version of uncompressed SD data format          CType         Short           compression type          EACRC         Long            CRC value for uncompressed SD data          (var.)        variable        compressed SD data          Central-header version:          Value         Size            Description          -----         ----            -----------  (SD)    0x4453        Short           tag for this extra block type          TSize         Short           total data size for this block          BSize         Long            size of uncompressed local SD data          The value of CType is interpreted according to the "compression          method" section above; i.e., 0 for stored, 8 for deflated, etc.          Version specifies how the compressed data are to be interpreted          and allows for future expansion of this extra field type.  Currently          only version 0 is defined.          For version 0, the compressed data are to be interpreted as a single          valid Windows NT SECURITY_DESCRIPTOR data structure, in self-relative          format.         -PKWARE Win95/WinNT Extra Field:          ==============================          The following description covers PKWARE's undocumented          Windows 95 & Windows NT extra field, introduced with the          release of PKZIP for Windows 2.50. (Last Revision 19980425)          This field has a fixed data size of 32 bytes and is only stored          as local extra field.          Value         Size            Description          -----         ----            ----------- (WinNT)  0x000a        Short           Tag for this "extra" block type          TSize         Short           Total Data Size for this block          Unknwn1       Long            ???? (all 0 ?)          Unknwn2       Long            ????          ModTime       Long-Long       64-bit NTFS last-modified filetime          AccTime       Long-Long       64-bit NTFS last-access filetime          CreTime       Long-Long       64-bit NTFS creation filetime          The NTFS filetimes are 64-bit unsigned integers, stored in Intel          (least significant byte first) byte order. They determine the          number of 1.0E-07 seconds (1/10th microseconds!) past WinNT "epoch",          which is "01-Jan-1601 00:00:00 UTC".         -PKWARE VAX/VMS Extra Field:          ==========================          The following is the layout of PKWARE's VAX/VMS attributes "extra"          block.  (Last Revision 12/17/91)          Note: all fields stored in Intel low-byte/high-byte order.          Value         Size            Description          -----         ----            -----------  (VMS)   0x000c        Short           Tag for this "extra" block type          TSize         Short           Total Data Size for this block          CRC           Long            32-bit CRC for remainder of the block          Tag1          Short           VMS attribute tag value #1          Size1         Short           Size of attribute #1, in bytes          (var.)        Size1           Attribute #1 data          .          .          .          TagN          Short           VMS attribute tage value #N          SizeN         Short           Size of attribute #N, in bytes          (var.)        SizeN           Attribute #N data          Rules:          1. There will be one or more of attributes present, which will             each be preceded by the above TagX & SizeX values.  These             values are identical to the ATR$C_XXXX and ATR$S_XXXX constants             which are defined in ATR.H under VMS C.  Neither of these values             will ever be zero.          2. No word alignment or padding is performed.          3. A well-behaved PKZIP/VMS program should never produce more than             one sub-block with the same TagX value.  Also, there will never             be more than one "extra" block of type 0x000c in a particular             directory record.         -Info-ZIP VMS Extra Field:          ========================          The following is the layout of Info-ZIP's VMS attributes extra          block for VAX or Alpha AXP.  The local-header and central-header          versions are identical.  (Last Revision 19960922)          Value         Size            Description          -----         ----            -----------  (VMS2)  0x4d49        Short           tag for this extra block type          TSize         Short           total data size for this block          ID            Long            block ID          Flags         Short           info bytes          BSize         Short           uncompressed block size          Reserved      Long            (reserved)          (var.)        variable        compressed VMS file-attributes block          The block ID is one of the following unterminated strings:                "VFAB"          struct FAB                "VALL"          struct XABALL                "VFHC"          struct XABFHC                "VDAT"          struct XABDAT                "VRDT"          struct XABRDT                "VPRO"          struct XABPRO                "VKEY"          struct XABKEY                "VMSV"          version (e.g., "V6.1"; truncated at hyphen)                "VNAM"          reserved          The lower three bits of Flags indicate the compression method.  The          currently defined methods are:                0       stored (not compressed)                1       simple "RLE"                2       deflated          The "RLE" method simply replaces zero-valued bytes with zero-valued          bits and non-zero-valued bytes with a "1" bit followed by the byte          value.          The variable-length compressed data contains only the data corre-          sponding to the indicated structure or string.  Typically multiple          VMS2 extra fields are present (each with a unique block type).         -Info-ZIP Macintosh Extra Field:          ==============================          The following is the layout of the (old) Info-ZIP resource-fork extra          block for Macintosh.  The local-header and central-header versions          are identical.  (Last Revision 19960922)          Value         Size            Description          -----         ----            -----------  (Mac)   0x07c8        Short           tag for this extra block type          TSize         Short           total data size for this block          "JLEE"        beLong          extra-field signature          FInfo         16 bytes        Macintosh FInfo structure          CrDat         beLong          HParamBlockRec fileParam.ioFlCrDat          MdDat         beLong          HParamBlockRec fileParam.ioFlMdDat          Flags         beLong          info bits          DirID         beLong          HParamBlockRec fileParam.ioDirID          VolName       28 bytes        volume name (optional)          All fields but the first two are in native Macintosh format          (big-endian Motorola order, not little-endian Intel).  The least          significant bit of Flags is 1 if the file is a data fork, 0 other-          wise.  In addition, if this extra field is present, the filename          has an extra 'd' or 'r' appended to indicate data fork or resource          fork.  The 28-byte VolName field may be omitted.         -ZipIt Macintosh Extra Field (long):          ==================================