The standard analysis of indefinites (e.g. Russell or more recently in the Discourse Representation Theory) views them as introducing a new discourse referent that is considered as independent from both the textual and extra-textual context. Still it can be observed that in many situations such as dialogue there are cases where sequences of indefinites are explicitly referring to the same entity, when for instance its properties have to be refined. On the basis of a corpus study of task-oriented dialogue transcriptions, we show that indefinites can only be coreferential if the events that bear them as arguments are coreferential as well. We thus identify the basic cues that may lead to the automatic determination of such situations (e.g. adverbials, sub-categorising statements etc.) and apply them to analyze our corpus examples. We also show that the configuration of dialogue acts (re-statements, question-answer pairs) directly influence the subsequent use of indefinite following an initial statement.