# Delimiters and Separating Data from Instructions — Prompt Engineering

Source: https://www.geekswithgeeks.com/en/prompt-engineering/c-delim

> Use tags, quotes or fences to mark the input clearly.

## Fences make boundaries obvious

Wrap variable content in clear **delimiters**: XML-style tags (`<document>...</document>`), triple quotes or Markdown code fences. Name the section in your instructions ("summarise the text inside `<document>` tags"). This prevents the model confusing a quoted email with your instructions, makes multi-part prompts readable, and lets you reference parts ("compare `<draft>` with `<policy>`"). It also helps with security: tell the model that the tagged content is **data** and any instructions inside it must be ignored (see the safety section).

## Tagged sections

Instructions refer to the tags by name.

```text
Compare the <draft> against the <policy> and list every violation.

<policy>
No promises of delivery dates. No personal data in replies.
</policy>

<draft>
Hi Asha, your order 4821 will arrive on Friday for sure.
</draft>
```

## Pick delimiters that cannot appear in the input

If the input could contain your closing tag, strip or escape it before wrapping, as the safety section shows.

**Quiz:** Why wrap input in tags?

- [ ] To change the language
- [ ] To compress the text
- [x] To mark clearly what is data and what are instructions
- [ ] To avoid tokens

*Answer:* To mark clearly what is data and what are instructions. Clear boundaries reduce confusion and injection risk.