To specify a default element to use for unmapped character formats:
[DocBookOptions]
; DefCharElem = element for char formats that are neither
; named for DocBook elements nor mapped in [DocBookCharTags]
DefCharElem = phrase
If your configuration file does not include a value for DefCharElem, DITA2Go uses one of the following as the element for an unmapped format: if UseFormatAsTag=Yes and the format name (adjusted as for CSS class names) matches the name of a valid element in the current content model, the format is mapped to that element; otherwise, the format is mapped to phrase, the default value of DefCharElem. See §26.4.1 Treating format names as element names.