  I/O conformance testing theories (e.g., ioco) are concerned with formally
defining when observable output behaviors of an implementation conform to those
permitted by a specification. Thereupon, several real-time extensions of ioco,
usually called tioco, have been proposed, further taking into account permitted
delays between actions. In this paper, we propose an improved version of tioco,
called live timed ioco (ltioco), tackling various weaknesses of existing
definitions. Here, a reasonable adaptation of quiescence (i.e., observable
absence of any outputs) to real-time behaviors has to be done with care: ltioco
therefore distinguishes safe outputs being allowed to happen, from live outputs
being enforced to happen within a certain time period thus inducing two
different facets of quiescence. Furthermore, tioco is frequently defined on
Timed I/O Labeled Transition Systems (TIOLTS), a semantic model of Timed I/O
Automata (TIOA) which is infinitely branching and thus infeasible for practical
testing tools. Instead, we extend the theory of zone graphs to enable ltioco
testing on a finite semantic model of TIOA. Finally, we investigate
compositionality of ltioco with respect to parallel composition including a
proper treatment of silent transitions.
