# The Annotation Guideline of LST20 Corpus

arXiv: https://arxiv.org/abs/2008.05055 · HTML: https://mlsanity.com/paper/2008.05055/

## Key facts

- Cited by 4 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 12 Aug 2020.

## Built on by (most cited first, 4 of 4)

- [PyThaiNLP: Thai Natural Language Processing in Python](https://mlsanity.com/paper/2312.04649/) (2023)
- [WangchanBERTa: Pretraining transformer-based Thai Language Models](https://mlsanity.com/paper/2101.09635/) (2021)
- [PhayaThaiBERT: Enhancing a Pretrained Thai Language Model with Unassimilated Loanwords](https://mlsanity.com/paper/2311.12475/) (2023)
- [ThaiTrees: Thai Syntactic Dependency Trees Across Domains](https://mlsanity.com/paper/2609.27558/) (2026)

## Abstract (arXiv)

This report presents the annotation guideline for LST20, a large-scale corpus with multiple layers of linguistic annotation for Thai language processing. Our guideline consists of five layers of linguistic annotation: word segmentation, POS tagging, named entities, clause boundaries, and sentence boundaries. The dataset complies to the CoNLL-2003-style format for ease of use. LST20 Corpus offers five layers of linguistic annotation as aforementioned. At a large scale, it consists of 3,164,864 words, 288,020 named entities, 248,962 clauses, and 74,180 sentences, while it is annotated with 16 distinct POS tags. All 3,745 documents are also annotated with 15 news genres. Regarding its sheer size, this dataset is considered large enough for developing joint neural models for NLP. With the existence of this publicly available corpus, Thai has become a linguistically rich language for the first time.