MICROSOFT EXCEL FILE FORMAT
Microsoft Excel is a popular spreadsheet. It uses a file format called BIFF (Binary
File Format). There are many types of BIFF records. Each has a 4 byte header. The
first two bytes are an opcode that specifies the record type. The second two bytes
specify record length. Header values are stored in byte-reversed form (less significant
byte first). The rest of the record is the data itself (Figure 2-1).
Figure 2-1. BIFF record header.
| Record Header | Record Body
Byte Number | 0 1 2 3 | 0 1 ...
-----------------------------------
Record Contents | XX | XX | XX | XX | XX | XX | ...
-----------------------------------
| opcode | length | data
Each X represents a hexadecimal digit
Two X's form a byte. The least significant (low) byte of the opcode is byte 0 and the
most significant (high) byte is byte 1. Similarly, the low byte of the record length
field is byte 2 and the high byte is byte 3.
BOF (Beginning of File)
