2.2.1.4.15.1 XPRESS Block Header

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Stores information about the data stored in an XPRESS Block.


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Block Signature

Block Compressed Size

Block Uncompressed Size

Block Signature (4 bytes): MUST be composed of the four bytes 0x58, 0x42, 0x4c, and 0x4f (or 'X', 'B', 'L', and 'O' in ASCII) as follows.


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0x58

0x42

0x4c

0x4f

Block Compressed Size (4 bytes): A 32-bit unsigned integer specifying the size of the XPRESS Block's data in bytes, regardless of whether it is compressed. The value of the Block Compressed Size field MUST be less than or equal to the value of the Block Uncompressed Size field and greater than 0.

Block Uncompressed Size (4 bytes): A 32-bit unsigned integer specifying the size of the XPRESS Block's data when uncompressed. The Block Uncompressed Size field MUST be less than or equal to 8,192 bytes.