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HNS2CF: A Mapping Tool from HamNoSys to SL CatForm

Paper · 2026 · Lisa Loy and Hope E. Morgan

Summary

Sign language forms are written down in many incompatible systems, which keeps datasets isolated from one another. Loy and Morgan revive the earlier SignTyp goal of linking notations and present HNS2CF, an automated Python tool that converts HamNoSys (version 3) transcriptions into strings of the newer SL CatForm phonological coding schema. SL CatForm, derived from Kenyan Sign Language analysis, uses fixed, independent variables grouped into six categories.

The authors compared both systems' documentation and found that some information maps directly, some exists in only one system, and some is only implicit. Syllable count, for example, is implicit in HamNoSys. They formalised four mapping relation types and evaluated the tool on German Sign Language (DGS) signs from the Public DGS Corpus. HNS2CF reaches 76.7% overall accuracy. Their error analysis shows that many mismatches come from disagreements between annotators rather than from faulty mapping, so the true accuracy is likely higher. The work shows that cross-notation mapping is feasible and is a step toward interoperable sign language resources.

Key points

  • Four mapping relation types: 1:1, n:1 (the most frequent), combination (a fixed set of HamNoSys characters), and pattern. A pattern match can either assign a value or split the HamNoSys string at a slicing point.
  • Two SL CatForm variables cannot be derived from HamNoSys: the secondary movement variable (#42) and the lexical mouthing variable (#6). They are kept in the output as "xx" placeholders.
  • Implementation: Six Python functions, one per SL CatForm category. The code is public on Codeberg (codeberg.org/lisaloy/HNS2CF).
  • Evaluation data: 100 DGS signs, about 4,100 data points. The HamNoSys data had multiple annotators, while the SL CatForm data had a single annotator, which the authors list as a limitation.
  • Planned extensions: A reverse mapping from SL CatForm to HamNoSys, coverage of other notation systems such as SignWriting, and integration into annotation pipelines.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

🎓Universität HamburgHamburg · Germany79 works · 5,422 citations

 Fields, topics and concepts

📚 Shelves 7The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 worksPsychology · 1,552 worksDevelopmental and Educational Psychology · 499 worksHuman-Computer Interaction · 141 works

Cite

Cite as Lisa Loy and Hope E. Morgan. 2026. HNS2CF: A Mapping Tool from HamNoSys to SL CatForm. Proceedings of the LREC 2026 12th Workshop on the Representation and Processing of Sign Languages: Language in Motion.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.63317/3m5m8sp4qe6j

@inproceedings{loy2026hns2cf,
  title = {{HNS2CF: A Mapping Tool from HamNoSys to SL CatForm}},
  author = {Lisa Loy and Hope E. Morgan},
  booktitle = {Proceedings of the LREC 2026 12th Workshop on the Representation and Processing of Sign Languages: Language in Motion},
  year = {2026},
  doi = {10.63317/3m5m8sp4qe6j},
  url = {https://doi.org/10.63317/3m5m8sp4qe6j}
}

References

17 references, 1 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

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