---
title: Custom Pre-Tokenized Dataset
description: How to use a custom pre-tokenized dataset.
order: 5
---

- Pass an empty `type:` in your axolotl config.
- Columns in Dataset must be exactly `input_ids`, `attention_mask`, `labels`
- To indicate that a token should be ignored during training, set its corresponding label to `-100`.
- Do not add BOS/EOS. Axolotl will add them for you based on the default tokenizer for the model you're using.
- For pretraining, do not truncate/pad documents to the context window length.
- For instruction training, documents must be truncated/padded as desired.

Sample config:

```{.yaml filename="config.yml"}
datasets:
  - path: /path/to/your/file.jsonl
    ds_type: json
    type:
```

Sample jsonl:

```jsonl
{"input_ids":[271,299,99],"attention_mask":[1,1,1],"labels":[271,-100,99]}
{"input_ids":[87,227,8383,12],"attention_mask":[1,1,1,1],"labels":[87,227,8383,12]}
```
