The properties you can specify for output formats are based on CSS rules, even if you are generating RTF output. If you are not familiar with CSS (Cascading Style Sheets), see §31.2 Understanding how to use CSS.
DITA2Go augments CSS rules with the following features:
Number streams (allowing more complexity than CSS permits)
Based formats, for incorporating properties of another format
Output-type-specific properties such as CSS and RTF
Content-adding properties such as Start, End, Before, After, Replace.
Format numbering is handled in the SubFormat templates. The idea is to provide building blocks, so you do not have to repeat the numbering properties in every block format that uses them.
Format property based allows you to base a format on the properties already defined for another format. See §7.4.5 Basing format properties on other formats.
Format property css allows you to assign any CSS to a format, for HTML output.
Format property rtf allows you to assign any RTF control words to a format, for RTF output. See §7.4.7 Applying CSS and RTF code to output formats.
Start, End, Before, After, Replace
Format properties start, end, before, and after add text or code around every instance of a format, and replace substitutes text or code for every instance. See §7.4.8 Assigning content-adding properties to formats.