The most commonly used PSL operator is the "suffix-implication" operator (a.k.a. the "triggers" operator), which is denoted by . Its left operand is a PSL regular expression and its right operand is any PSL formula (be it in LTL style or regular expression style). The semantics of is that on every time point i such that the sequence of time points up to i constitute a match to the regular expression r, the path from i+1 should satisfy the property p. This is exemplified in the figures on the right.