LTEM: LLM-Friendly Table-Enhanced Markdown for Table Understanding and Generation

Eunbin Kim, Hyeonseok Kang, Sangkeun Jung


Abstract
Tables in real-world documents, including scientific papers, financial reports, and statistical summaries, frequently use merged cells, multi-level headers, and sectioned layouts. Yet the lightweight formats LLMs handle best (Markdown, CSV) cannot express these structures, while expressive formats (HTML, LaTeX) impose excessive token cost and parsing complexity. To enable systematic analysis of this trade-off, we introduce a taxonomy decomposing table structure into six atomic features (F1–F6) and corresponding complexity levels (L1–L6), and construct STB (Synthetic Table Benchmark), a controlled benchmark with 1,089 tables systematically distributed across complexity levels. Using this framework, we propose LTEM (LLM-friendly Table-Enhanced Markdown), a formally specified, minimal extension of Markdown that explicitly encodes spans and hierarchical headers. Experiments across five state-of-the-art LLMs show that LTEM achieves accuracy comparable to HTML, offers a favorable accuracy–token trade-off relative to HTML and LaTeX, and produces substantially fewer invalid responses than LaTeX; for table generation, LTEM is comparable to MultiMarkdown though HTML is best. We release our taxonomy, benchmark, and format specification to support future research on LLM-table interaction.
Anthology ID:
2026.emnlp-main.1900
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:
43304–43324
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1900/
DOI:
Bibkey:
Cite (ACL):
Eunbin Kim, Hyeonseok Kang, and Sangkeun Jung. 2026. LTEM: LLM-Friendly Table-Enhanced Markdown for Table Understanding and Generation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 43304–43324, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
LTEM: LLM-Friendly Table-Enhanced Markdown for Table Understanding and Generation (Kim et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1900.pdf