offset of start of central directory with respect to
the starting disk number: (4 bytes)
Offset of the start of the central directory on the
disk on which the central directory starts. If an
archive is in zip64 format and the value in this
field is 0xFFFFFFFF, the size will be in the
corresponding 8 byte zip64 end of central
directory field.
.ZIP file comment length: (2 bytes)
The length of the comment for this .ZIP file.
.ZIP file comment: (Variable)
The comment for this .ZIP file. ZIP file comment data
is stored unsecured. No encryption or data authentication
is applied to this area at this time. Confidential information
should not be stored in this section.
zip64 extensible data sector (variable size)
(currently reserved for use by PKWARE)
K. General notes:
1) All fields unless otherwise noted are unsigned and stored
in Intel low-byte:high-byte, low-word:high-word order.
2) String fields are not null terminated, since the
length is given explicitly.
3) Local headers should not span disk boundaries. Also, even
though the central directory can span disk boundaries, no
single record in the central directory should be split
across disks.
4) The entries in the central directory may not necessarily
be in the same order that files appear in the .ZIP file.
5) Spanned/Split archives created using PKZIP for Windows
(V2.50 or greater), PKZIP Command Line (V2.50 or greater),
or PKZIP Explorer will include a special spanning
signature as the first 4 bytes of the first segment of
the archive. This signature (0x08074b50) will be
followed immediately by the local header signature for
the first file in the archive. A special spanning
marker may also appear in spanned/split archives if the
spanning or splitting process starts but only requires
one segment. In this case the 0x08074b50 signature
will be replaced with the temporary spanning marker
signature of 0x30304b50. Spanned/split archives
created with this special signature are compatible with
all versions of PKZIP from PKWARE. Split archives can
only be uncompressed by other versions of PKZIP that
know how to create a split archive.
6) If one of the fields in the end of central directory
record is too small to hold required data, the field
should be set to -1 (0xFFFF or 0xFFFFFFFF) and the
Zip64 format record should be created.
7) The end of central directory record and the
Zip64 end of central directory locator record must
reside on the same disk when splitting or spanning
an archive.
