Is there a standard (or at least common) symbol in computability theory used to indicate that $x$ enters the c.e. set $W_e$ at stage $s$, i.e., $x \in W_{e,s} - W_{e,s-1}$ (at least for $s \neq 0$)?

I was thinking of using $x \searrow_s W_e$ but I was worried that would be too confusing with its use in the automorphisms of $\mathscr{E}$ (i.e. $X \searrow Y$ are the elements that enter $X$ and then $Y$ (and I vaguely remember that $X \searrow_s Y$ is used for something).

Any suggestions for good notation? I'd consider using just use $x \in W_{e,s} - W_{e,s-1}$ (though a binary relation would be nicer) except for the annoying need to adopt the convention that $s$ can't be zero.