Using a text editor (e.g. WordPad) open up one of the HTML files from the demo collection: Greenstone → collect → demo → import → fb33fe →fb33fe.htm. You will see some HTML comments which contain section information for Greenstone. They look like:
<!--
<Section>
<Description>
<Metadata name="Title">Farming snails 1: Learning about snails;
Building a pen; Food and shelter plants</Metadata>
</Description>
-->
<!--
</Section>
<Section>
<Description>
<Metadata name="Title">Dew and rain</Metadata>
</Description>
-->
When Greenstone encounters a <Section> tag in one of these comments, it will start a new subsection of the document. This will be closed when a </Section> tag is encountered. Metadata can also be added for each section—in this case, Title metadata has been added for each section. In the browser, find the Farming snails 1 document in the demo collection (through the Titles A-Z browser). Look at its table of contents and compare it to the <Section> tags in the HTML document.