An aut, by which an avout is called forth (evoked) from his or her concent by the Saecular authorities. Typically this is done when the Saecular authorities need an expert to solve a particular real-world problem. All avout must attend this aut, in case their name is called, even if the avout is currently restricted to a cell to do penance.
The evoked avout leaves their Math immediately, and to the others, it is as though they died, as they will not be seen again. The math which gives up its member sings a powerful song of mourning during the aut.
The avout are uncertain of how the Saeculars know who to evoke, particularly when one is evoked from the Centenarian or Millenarian Maths. It is suspected that the Ita may provide intelligence on avout activities to the saecular power.
The word "Voco" is latin for "to summon" or "to call forth." It is used here, presumably to say one is being called forth or summoned into the Saecular world.