For text elements, table elements, and cross references, you can map the outputclass attribute of the element to an output format. However, mapping outputclass attributes does not apply to all elements. Among those excluded are typographic elements, such as <b> and <i>. Those are treated as properties, rather than as formats. Others excluded are <ftn>, <image>, <alt>, and <index*>. All undergo special processing of one sort or another. For <ftn>, DITA2Go automatically uses the value of the outputclass attribute as the output format name.
§6.3.1 Mapping block and inline outputclass attributes to formats
§6.3.2 Mapping table outputclass attributes to formats
§6.3.3 Mapping cross-reference outputclass attributes to formats
§6.3.4 Mapping wrapper-element outputclass attributes to formats