To specify a (sub-) section of a zettel, you should use the headings syntax: at the beginning of a new line type at least three equal signs (“=”, U+003D), plus at least one space and enter the text of the heading as inline elements.

=== Level 1 Heading
==== Level 2 Heading
===== Level 3 Heading
====== Level 4 Heading
======= Level 5 Heading
======== Level 5 Heading

This renders in HTML as:

Notes

The heading level is translated to a HTML heading by adding 1 to the level, e.g. === Level 1 Heading translates to <h2>Level 1 Heading</h2>. The <h1> tag is rendered for the zettel title.

This syntax is often used in a similar way in wiki implementation. However, trailing equal signs are not removed, they are part of the heading text.

If you use command line tools, you can easily create a draft table of contents with the command:

grep -h '^====* ' ZETTEL_ID.zettel