A sequence flow object class is formatted to produce the concatenation of the areas produced by each of its children. It has a single principal port. Its children may be inlined or displayed.
NOTE 55: A sequence flow object is useful for specifying inherited characteristics. For example, a sequence flow object with a specification of a font-posture: characteristic may be constructed for an emphasized phrase element in a paragraph.
A port of a flow object shall accept a sequence flow object if and only if it would accept each of the flow objects in that sequence.