enhancement: GS1 DataBar missing Truncated, Stacked, Stacked Omnidirectional, and Expanded Stacked variants

[productdevbook]

Summary

The GS1 DataBar implementation only includes 3 of the 7 variants defined in ISO/IEC 24724. The missing variants are important for retail and supply chain applications.

Missing variants

1. GS1 DataBar Truncated — Same encoding as Omnidirectional but with reduced height (13 modules instead of 33). Used where space is constrained but omnidirectional scanning isn't needed.

2. GS1 DataBar Stacked — Two-row version of Omnidirectional. Required for small packages where a single row doesn't fit.

3. GS1 DataBar Stacked Omnidirectional — Two-row version with full-height rows for omnidirectional scanning. Common in retail produce.

4. GS1 DataBar Expanded Stacked — Multi-row version of Expanded. Essential for encoding long AI strings (e.g., weight, expiry date) on small packages. Widely used in variable-weight produce labeling.

Currently implemented

• ✅ GS1 DataBar Omnidirectional
• ✅ GS1 DataBar Limited
• ✅ GS1 DataBar Expanded

Priority

Expanded Stacked is the highest priority as it's the most commonly used variant in retail produce and fresh food labeling worldwide.

References

• ISO/IEC 24724:2011
• GS1 DataBar family overview
• GS1 General Specifications Section 5.5