It should allocate the full Content Display Area for the document, as defined in Viewport Rendering. (idpf.org)
Another aspect that sets the CST - 100 apart from past vessels is the number and size of viewports. (extremetech.com)
Furthermore, this specification allows Authors to define a condensed entry designed specifically for ease of reading in a lookup viewport [ContentDocs301]; refer to Condensed and Detailed Entries for details. (idpf.org)