The Rocket eBook only supports a subset of HTML 3.2's tags. However, if you're authoring your own content, you should keep things fairly simple. B Mark bold text. BIG Switch to the large font. BR Force a line break.
CODE Use a fixed-pitch font for the enclosed text.
The definition in a defined list. The topic in a defined list. EM Enclose emphasized text. HR A horizontal ruler. This tag should enclose the entire document.