What are the used activity diagram constructs? a survey

UML Activity diagrams offer a very large set of constructs, however many of them seem scarcely used or even their existence is not known. Here, we present a precise view of the usage levels of these constructs by means of a survey, covering preliminarily books, courses, tutorials, and tools about UML. Results show that, among the 47 Activity diagrams constructs, a large majority of them seem to be scarcely used, while, only nine result widely used. This work is part of a larger project aimed at investigating the usage level of the UML diagrams and their constructs, also by means of a personal opinion survey intended for UML users. UML is really a huge notation, and as consequence, on one hand, it is difficult and time consuming to master it, and on the other hand, people tend, naturally, to consider only a part of it; by means of this empirical study we want to assess what are the most/less used UML diagrams/constructs.