What is the SDC file format?
.sdc is the native spreadsheet format of StarCalc, the spreadsheet component of StarOffice and its predecessor StarDivision Office. StarDivision GmbH (Hamburg, Germany) introduced the format around 1994 with StarCalc 3.0, and it remained the primary spreadsheet container through StarOffice 5.x (1999).
Internally, .sdc files from StarCalc 4.x and 5.x use the OLE2 Compound File Binary Format (CFBF) - the same container shared by XLS and classic .doc files - identifiable by the eight-byte magic sequence D0 CF 11 E0 A1 B1 1A E1 at offset zero. Inside the compound document, the StarCalcDocument stream holds cell data, formulas, and charts in a binary grid, while separate streams carry styles, StarBasic macros, and document metadata. Earlier StarCalc 3.x files use a simpler binary container opening with an SLD2 header rather than the OLE2 wrapper.
Sun Microsystems acquired StarDivision in 1999 and released the source as OpenOffice.org in 2000. OpenOffice.org 1.x introduced the intermediate .sxc XML format, and the suite moved to the open ODS standard from version 2.0 (2005) onwards, making .sdc obsolete. LibreOffice Calc retains the ability to open .sdc files today.
Note that .sdc is also used by unrelated applications - including SmartWare database files - so the MIME type application/vnd.stardivision.calc or the internal OLE2 GUID c6a5b861-85d6-11d1-89cb-008029e4b0b1 is needed for reliable identification.
Security & safety
RISK: MEDIUMSDC files can contain embedded StarBasic macros (BasicManager2 stream), which LibreOffice will prompt to enable/disable. Do not enable macros from untrusted sources. OLE2 compound files can in theory contain embedded objects; scan untrusted files with antivirus.
Format details
in a nutshell- SmartWare Database - Older Angoss SmartWare database software used .sdc for data tables; unrelated to StarOffice.
Programs that open SDC files
Windows3 apps
LibreOffice Calc
Open-source File > Open > select the .sdc file; LibreOffice Calc opens it with backward compatibility. 
Apache OpenOffice Calc
Open-source File > Open > select the .sdc file; Apache OpenOffice retains legacy StarCalc import.
SoftMaker FreeOffice (PlanMaker)
Free Open .sdc via File > Open in PlanMaker; may have limited fidelity for older StarCalc features. 
macOS3 apps
Linux2 apps
Technical details
deep spec| Container format | OLE2 Compound File Binary Format (CFBF) |
| Magic bytes | `D0 CF 11 E0 A1 B1 1A E1` at offset 0 (OLE2 signature) |
| Internal GUID | `c6a5b861-85d6-11d1-89cb-008029e4b0b1` (StarCalc 5.x stream identifier) |
| Older variant header | `SLD2` magic (StarCalc 3.x, non-OLE2 binary container) |
| MIME type | `application/vnd.stardivision.calc` |
| Byte order | Little-endian |
| Encryption | Optional document-level password protection |
| Typical file size | 10 KB - 5 MB |
| Cell data stream | `StarCalcDocument` (binary row/column grid with typed values, formulas, charts) |
| Macro language | StarBasic (stored in `BasicManager2` OLE2 stream) |
| Associated OS | Windows, Linux, macOS, Solaris |
| Superseded by | ODS (OpenDocument Spreadsheet) from OpenOffice.org 2.0 (2005); `.sxc` XML was the intermediate format in OpenOffice.org 1.x |
| Developer lineage | StarDivision GmbH → Sun Microsystems (1999) → Oracle (2010); source released as OpenOffice.org (2000) |
| Released | 1994 (StarCalc 3.0); format used through StarOffice 5.x (1999) |
| Latest version | StarCalc 5.x (last .sdc variant, circa 1999); superseded by ODS in OpenOffice.org 1.0 (2002) |
SDC conversions
Community Q&A
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