there are no such functions, some time ago Spark did accept for bold / italic / underline but also these functions were removed.
One could write a Sparkplug to add such functions, in Spark itself they will probably never be available as these format options are in no JEP defined.
Future versions of Spark will be supporting xhtml to allow for such things in a more formal way. The one thing I am adding at this time is the simple mappings such as /me, etc.