> 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/preface/notation.md).

# 3. Conventions \#

The following conventions are used in the synopsis of a command: brackets (`[` and `]`) indicate optional parts. Braces (`{` and `}`) and vertical lines (`|`) indicate that you must choose one alternative. Dots (`...`) mean that the preceding element can be repeated. All other symbols, including parentheses, should be taken literally.

Where it enhances the clarity, SQL commands are preceded by the prompt `=>`, and shell commands are preceded by the prompt `$`. Normally, prompts are not shown, though.

An *administrator* is generally a person who is in charge of installing and running the server. A *user* could be anyone who is using, or wants to use, any part of the PostgreSQL system. These terms should not be interpreted too narrowly; this book does not have fixed presumptions about system administration procedures.

***

原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/notation.html)（英文原文，待翻譯）


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