> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/appendixes/docguide/j.1.-docbook.md).

# J.1. DocBook

The documentation sources are written in *DocBook*, which is a markup language defined in XML. In what follows, the terms DocBook and XML are both used, but technically they are not interchangeable.

DocBook allows an author to specify the structure and content of a technical document without worrying about presentation details. A document style defines how that content is rendered into one of several final forms. DocBook is maintained by the [OASIS group](https://www.oasis-open.org/). The [official DocBook site](https://www.oasis-open.org/docbook/) has good introductory and reference documentation and a complete O'Reilly book for your online reading pleasure. The [NewbieDoc Docbook Guide](http://newbiedoc.sourceforge.net/metadoc/docbook-guide.html) is very helpful for beginners. The [FreeBSD Documentation Project](https://www.freebsd.org/docproj/) also uses DocBook and has some good information, including a number of style guidelines that might be worth considering.


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# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.postgresql.tw/appendixes/docguide/j.1.-docbook.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.