|DITA map files / Topic hierarchy|
The topic hierarchy in the ditamap is used to generate heading levels and styles in page layout outputs.
In DITA, each topic is written as a standalone chunk of content. The style in which a topic title, for example, is eventually presented to the user is determined by the position of the topic in the relevant ditamap.
Camera Model 700 > Storing Pictures > Memory > About SD Cardsthen its heading style in RTF output might be Heading 4.
Taking Pictures > Storing > About SD Cardsthen its heading style in RTF output might be Heading 3. The topic is identical, but its presentation is appropriate to the output context.
And it gets better! Topic titles can be different in different ditamaps.