The structure of a document is determined by its headers. Headers (heads) are created with the commands shown below:

\chapter \title
\section \subject
\subsection \subsubject
\subsubsection \subsubsubject
... ...

These commands will produce a header in a predefined font size and font type with some vertical spacing before and after the header.

The heading commands can take several arguments, like in:

```\setuppapersize[A5]
\title[hasselt-by-night]{Hasselt by night}
```

and

```\setuppapersize[A5]
\title{Hasselt by night}
```

The bracket pair is optional and used for internal references. If you want to refer to this header you type for example `\at{page}[hasselt-by-night]`.

Of course these headers can be set to your own preferences and you can even define your own headers. This is done by the command \setuphead and \definehead.

```\definehead
[section]

[numberstyle=bold,
textstyle=bold,
before=\hairline\blank,
after=\nowhitespace\hairline]

```

A new header `\myheader` is defined and it inherits the properties of \section. It would look something like this:

There is one other command you should know now, and that is \setupheads. You can use this command to set up the numbering of the numbered headers. If you type:

```\setupheads
[alternative=inmargin,
separator=--]
```

all numbers will appear in the margin. Section 1.1 would look like 1--1.

Commands like \setupheads are typed in the set up area of your input file.