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2.2.2.6 HEADER

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The HEADER structure is located at the beginning of the PST file (absolute file offset 0), and contains metadata about the PST file, as well as the ROOT information to access the NDB Layer data structures. Note that the layout of the HEADER structure, including the location and relative ordering of some fields, differs between the Unicode and ANSI versions.

Unicode:


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dwMagic

dwCRCPartial

wMagicClient

wVer

wVerClient

bPlatformCreate

bPlatformAccess

dwReserved1

dwReserved2

bidUnused

...

bidNextP

...

dwUnique

rgnid[] (128 bytes)

...

root (76 bytes)

rgbFM (128 bytes)

...

rgbFP (128 bytes)

...

bSentinel

bCryptMethod

rgbReserved

bidNextB

dwCRCFull

rgbReserved2

bReserved

rgbReserved3 (32 bytes)

...

ANSI:


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dwMagic

dwCRCPartial

wMagicClient

wVer

wVerClient

bPlatformCreate

bPlatformAccess

dwReserved1

dwReserved2

bidNextB

bidNextP

dwUnique

rgnid[] (128 bytes)

...

root (40 bytes)

...

rgbFM (128 bytes)

...

rgbFP (128 bytes)

...

bSentinel

bCryptMethod

rgbReserved

ullReserved

...

dwReserved

rgbReserved2

bReserved

rgbReserved3 (32 bytes)

...

dwMagic (4 bytes): MUST be "{ 0x21, 0x42, 0x44, 0x4E } ("!BDN")".

dwCRCPartial (4 bytes): The 32-bit cyclic redundancy check (CRC) value of the 471 bytes of data starting from wMagicClient (0ffset 0x0008)

wMagicClient (2 bytes): MUST be "{ 0x53, 0x4D }".

wVer (2 bytes): File format version. This value MUST be 14 or 15 if the file is an ANSI PST file, and MUST be 23 if the file is a Unicode PST file.

wVerClient (2 bytes): Client file format version. The version that corresponds to the format described in this document is 19. Creators of a new PST file based on this document SHOULD initialize this value to 19.

bPlatformCreate (1 byte): This value MUST be set to 0x01.

bPlatformAccess (1 byte): This value MUST be set to 0x01.

dwReserved1 (4 bytes): Implementations SHOULD ignore this value and SHOULD NOT modify it. Creators of a new PST file MUST initialize this value to zero.<8>

dwReserved2 (4 bytes): Implementations SHOULD ignore this value and SHOULD NOT modify it. Creators of a new PST file MUST initialize this value to zero.<9>

bidUnused (8 bytes Unicode only): Unused padding added when the Unicode PST file format was created.

bidNextP (Unicode: 8 bytes; ANSI: 4 bytes): Next page BID. Pages have a special counter for allocating bidIndex values. The value of bidIndex for BIDs for pages is allocated from this counter.

bidNextB (4 bytes ANSI only): Next BID. This value is the monotonic counter that indicates the BID to be assigned for the next allocated block. BID values advance in increments of 4. For more details, see section 2.2.2.2.

dwUnique (4 bytes): This is a monotonically-increasing value that is modified every time the PST file's HEADER structure is modified. The function of this value is to provide a unique value, and to ensure that the HEADER CRCs are different after each header modification.

rgnid[] (128 bytes): A fixed array of 32 NIDs, each corresponding to one of the 32 possible NID_TYPEs (section 2.2.2.1). Different NID_TYPEs can have different starting nidIndex values. When a blank PST file is created, these values are initialized by NID_TYPE according to the following table. Each of these NIDs indicates the last nidIndex value that had been allocated for the corresponding NID_TYPE. When an NID of a particular type is assigned, the corresponding slot in rgnid is also incremented by 1.

NID_TYPE

Starting nidIndex

NID_TYPE_NORMAL_FOLDER

1024 (0x400)

NID_TYPE_SEARCH_FOLDER

16384 (0x4000)

NID_TYPE_NORMAL_MESSAGE

65536 (0x10000)

NID_TYPE_ASSOC_MESSAGE

32768 (0x8000)

Any other NID_TYPE

1024 (0x400)

qwUnused (8 bytes): Unused space; MUST be set to zero. Unicode PST file format only.

root (Unicode: 72 bytes; ANSI: 40 bytes): A ROOT structure (section 2.2.2.5).

dwAlign (4 bytes): Unused alignment bytes; MUST be set to zero. Unicode PST file format only.

rgbFM (128 bytes): Deprecated FMap. This is no longer used and MUST be filled with 0xFF. Readers SHOULD ignore the value of these bytes.

rgbFP (128 bytes): Deprecated FPMap. This is no longer used and MUST be filled with 0xFF. Readers SHOULD ignore the value of these bytes.

bSentinel (1 byte): MUST be set to 0x80.

bCryptMethod (1 byte): Indicates how the data within the PST file is encoded. MUST be set to one of the pre-defined values described in the following table.

Value

Friendly name

Meaning

0x00

NDB_CRYPT_NONE

Data blocks are not encoded.

0x01

NDB_CRYPT_PERMUTE

Encoded with the Permutation algorithm (section 5.1).

0x02

NDB_CRYPT_CYCLIC

Encoded with the Cyclic algorithm (section 5.2).

rgbReserved (2 bytes): Reserved; MUST be set to zero.

bidNextB (8 bytes): Indicates the next available BID value. Unicode PST file format only.

bidNextB (Unicode ONLY: 8 bytes): Next BID. This value is the monotonic counter that indicates the BID to be assigned for the next allocated block. BID values advance in increments of 4. For more details, see section 2.2.2.2.

dwCRCFull (4 bytes): The 32-bit CRC value of the 516 bytes of data starting from wMagicClient to bidNextB, inclusive. Unicode PST file format only.

ullReserved (8 bytes): Reserved; MUST be set to zero. ANSI PST file format only.

dwReserved (4 bytes): Reserved; MUST be set to zero. ANSI PST file format only.

rgbReserved2 (3 bytes): Implementations SHOULD ignore this value and SHOULD NOT modify it. Creators of a new PST MUST initialize this value to zero.<10>

bReserved (1 byte): Implementations SHOULD ignore this value and SHOULD NOT modify it. Creators of a new PST file MUST initialize this value to zero.<11>

rgbReserved3 (32 bytes): Implementations SHOULD ignore this value and SHOULD NOT modify it. Creators of a new PST MUST initialize this value to zero.<12>

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