true if CRDT checks preconditions.
Update phase 1 ("atSource").
This mechanism allows to discard stable operations, not only timestamps, if they have no impact on the semantics of the data type.
the TCStable delivered by the TCSB middleware
the crdt after being applied causal stabilization. By default it returns the same crdt unmodified
Returns the CRDT value (for example, the entries of an OR-Set)