Using the alternatives (alt) tier in ToBI transcriptions allows labellers to capture annotation ambiguities explicitly; this labelling innovation allows researchers to address several open research questions concerning prosodic phonology. Furthermore, the standard alt notation allows this data to be shared among researchers and to be machine-readable for the examination of large labelled corpora. Finally, it is anticipated that having an alt tier to record competing labels will facilitate faster and more reliable hand annotation. This paper reports on the use of the alt tier in a large speech sample labelled by 4 expert annotators.