One or more groups, each consisting of two parts: The base text, which is either: Phrasing content, but with no elements and with no element descendants, or A single element that itself has no element descendants. The annotations for the base text, which is either: One or more elements, or An element followed by one or more elements, each of which is itself followed by an element (that is, rp, rt, rp, rt, ..., rp).
Tag omission
None, both the starting and ending tag are mandatory.