2.2.1 File Type Identifier
The file type identifier is a structure stored at offset zero of the file.
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Signature |
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Creator (512 bytes) |
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Signature (8 bytes): MUST be 0x7668647866696C65, which is a UTF-8 string representing "vhdxfile".
Creator (512 bytes): Contains a UTF-16 string that can be null terminated. This field is optional; the implementation fills it in during the creation of the VHDX file to identify, uniquely, the creator of the VHDX file. Implementation MUST NOT use this field as a mechanism to influence implementation behavior; it exists for diagnostic purposes only.
An implementation MUST write the File Type Identifier structure when the file is created and MUST validate the Signature field when loading a VHDX file. The implementation MUST NOT overwrite any data in the first 64 KB of the file after the file has been created.
The space between file identifier data and 64-KB alignment boundary for the file identifier structure is reserved.