  Temporal relations between events and time expressions in a document are
often modeled in an unstructured manner where relations between individual
pairs of time expressions and events are considered in isolation. This often
results in inconsistent and incomplete annotation and computational modeling.
We propose a novel annotation approach where events and time expressions in a
document form a dependency tree in which each dependency relation corresponds
to an instance of temporal anaphora where the antecedent is the parent and the
anaphor is the child. We annotate a corpus of 235 documents using this approach
in the two genres of news and narratives, with 48 documents doubly annotated.
We report a stable and high inter-annotator agreement on the doubly annotated
subset, validating our approach, and perform a quantitative comparison between
the two genres of the entire corpus. We make this corpus publicly available.
