The user may define subclasses of this class.
A may occur entirely before or after B, or have some degree of temporal coincidence with B. The possible values for sequence, as defined in the enumeration Succession, are before, after, and coincident.
before: A and B do not intersect temporally, and any temporal point (start, end or a point on the included interval) on A comes before any point on B.
after: A and B do not intersect temporally, and any temporal point on A comes before any point on B.
coincident: A and B intersect temporally. That is, there is at least one temporal point on A which is simultaneous with a point on B.