An occurrence trigger theory that charges the loss against any policy in force from the time of first exposure to a harmful situation to the time of manifestation of the injury or disease. Triple is derived from: (a) initial exposure; (b) continuing exposure (injury-in-residence); and (c) manifestation. The theory triggers any policy for its full limit not just a share. The insured can select which policies should respond with the possibility of stacking limits, aggregate limits of indemnity from different policy years. The theory has not been uniformly adopted across the US, its birthplace. Other theories, e.g exposure theory, injury-in-fact theory, and the manifestation theory, have also found favour. Insurers use a claims series clause in order to trigger continuing losses from one original cause into the policy year of first occurrence. See also BATCH CLAUSE; LIABILITY SEQUENCE.