As for snapshot equivalent and weakly equivalent, both names have strong support by members of the temporal database community. Because it has not been possible to reach a consensus on which of these two names is preferable, both have been adopted in alphabetical order.
``Weak relation'' denotes a set of relation instances, not a single relation instance. It has therefore been argued that the name snapshot equivalence class is more intuitive. On the other hand, ``weak relation'' is shorter than ``snapshot equivalence class.''