OASIS (Open Artwork System Interchange Standard) is the successor to GDSII, designed to address its limitations. Defined by SEMI standard P39, OASIS provides superior compression and removes many GDSII constraints.
| Property | Value |
|---|
| Extensions | .oasis, .oas |
| Encoding | Binary (compressed) |
| Import | ✓ |
| Export | ✓ |
| License | Basic |
| Hierarchy | Full cell hierarchy |
| Layers | Numeric layers with datatypes |
Import Options
| Option | Description | Default |
|---|
| Ignore text elements | Skip text records during import | Off |
Supported Features
- All geometry types (polygon, path, trapezoid, CTrapezoid, circle, text)
- Cell hierarchy with placements
- Repetitions (OASIS equivalent of GDSII AREFs)
- Properties and S_* system properties
- Compressed cells
- Layer/datatype pairs
- XGeometry records
Export Options
| Option | Description | Default |
|---|
| Database units | Internal coordinate resolution | 1 nm |
| Compression | Enable DEFLATE compression for smaller files | On |
| Flatten hierarchy | Expand all cell references | Off |
GDSII vs OASIS
| Feature | GDSII | OASIS |
|---|
| File size | Large | 5–20× smaller |
| Max polygon vertices | 8191 | Unlimited |
| Layer range | 0–65535 | 0–2³²-1 |
| Compression | None | Built-in DEFLATE |
| Repetitions | AREF only (rectangular) | Arbitrary repetitions |
Common Workflows
OASIS → GDSII
Standard conversion from compact OASIS back to widely-supported GDSII. Note that OASIS polygons exceeding 8191 vertices will be automatically split.
GDSII → OASIS
Compress large GDSII files for archival or transfer. Typical compression ratios are 5:1 to 20:1.
Technical Notes
- OASIS is defined by SEMI standard P39-0707
- Files can contain both compressed and uncompressed cells
- Strict mode validates file checksums (CRC32)
- OASIS supports far larger designs than GDSII due to built-in compression
