The Microsoft Excel File Format - OpenOffice.org

4.10 Internal and External References
4.10.3 References in BIFF8
The main data of all types of references is stored in the Link Table inside the Workbook Globals Substream (➜4.2.5). All
formulas use only indexes for specific references. The Link Table itself is optional and occurs only, if there are any
references in the document.
Common structure of the Link Table, BIFF8:
●● EXTERNALBOOK Blocks Settings for a referenced document
● EXTERNSHEET ➜5.41
○○ DEFINEDNAME ➜5.33
Each referenced document is represented by an EXTERNALBOOK Block. It starts with an EXTERNALBOOK record. It
contains the name of the document and the names of its sheets. It is followed by additional records that allow to dereference
the data in the document. After the last EXTERNALBOOK Block occurs only one EXTERNSHEET record. It
contains a list with indexes to the SUPBOOKs for each used reference anywhere in the document. Formulas use indexes
into this EXTERNSHEET list.
Example: A document contains (among other references) the two formulas
=[example.xls]ExtSheet2!A1 and
=[example.xls]ExtSheet1!A1.
EXTERNALBOOK
Block 0
EXTERNALBOOK
Block 1
EXTERNALBOOK
Block 2
EXTERNSHEET
Any content
Document = “example.xls”
Sheet 0 = “ExtSheet1”
Sheet 1 = “ExtSheet2”
Sheet 2 = “ExtSheet3”
Any content
REF 0 = any reference
REF 1 = {EXTERNALBOOK = 1, sheet range = 1…1}
REF 2 = any reference
REF 3 = {EXTERNALBOOK = 1, sheet range = 0…0}
REF 4 = any reference
The first formula uses REF 1 in the EXTERNSHEET record. REF 1 refers to EXTERNALBOOK Block 1 and
sheet range 1…1. This means, the document “example.xls” is used (document of EXTERNALBOOK Block 1)
and the name of the sheet is “ExtSheet2” (sheet 1 of EXTERNALBOOK Block 1). In the same way, the second
formula uses REF 3 in the EXTERNSHEET record. All list entries inside of the EXTERNSHEET record are
unique. For instance all formulas in the workbook referring to sheet “ExtSheet2” of the document “example.xls”
use REF 1. All other EXTERNALBOOK Blocks and REFs are placeholders for other references in this example.
Common structure of an EXTERNALBOOK Block, BIFF8:
● EXTERNALBOOK ➜5.38
○○ EXTERNALNAME ➜5.39
○○
● XCT ➜5.114
●● CRN ➜5.23
The EXTERNALBOOK Block may contain cached values of cells in the referenced document. These values are stored in
several XCT and CRN records.
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