Notation for the projection of a relation onto one component space

Question

Suppose $R \subseteq S \times T$, i.e. $R$ is a relation between $S$ and $T$.

What is the notation for the projection of $R$ onto $T$, i.e. for $\{t: \forall t \in T, \exists s \in S, s.t. (s,t) \in R \}$?

Is it $R_T$?

Thanks.