NEST: A Benchmark for Explicit Structural Parsing on Native Empty Templates

Chen Peng, Tianci He, Hongye Chen, Jiayi Huang, Kangdi Hao, Yiping Song


Abstract
Certain document automation scenarios, such as intelligent form infilling and privacy-strict parsing, require models to comprehend unpopulated templates. Yet existing benchmarks mainly use content-filled tables, leaving the template side of document understanding under-evaluated. To bridge this gap, we introduce NEST, a benchmark of 828 Native Empty Structural Templates from real-world, born-digital forms. NEST removes filled content while preserving complex hierarchical layouts and guided selection options in authentic administrative workflows. Through Structural Schema Parsing, Cell-Header Alignment, and Generative Infilling, NEST directly evaluates structural reasoning without content-based shortcuts. Experiments reveal a clear template–instance gap: state-of-the-art LLMs drop by 9.5 percentage points on average when evaluated on unpopulated templates rather than populated instances. We further show that Generative Infilling is a data-efficient tuning signal for template completion, raising infilling accuracy by 16.37 percentage points and the three-task average by 8.19 percentage points with only 662 (80%) training templates. NEST thus provides a benchmark for measuring template-level understanding and highlights a data-efficient route for improving template completion. The code, data, and results for this paper are available at https://github.com/cpeng-research/NEST-Benchmark.
Anthology ID:
2026.emnlp-main.1010
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
23248–23263
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1010/
DOI:
Bibkey:
Cite (ACL):
Chen Peng, Tianci He, Hongye Chen, Jiayi Huang, Kangdi Hao, and Yiping Song. 2026. NEST: A Benchmark for Explicit Structural Parsing on Native Empty Templates. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 23248–23263, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
NEST: A Benchmark for Explicit Structural Parsing on Native Empty Templates (Peng et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1010.pdf