Hey folks, if I attempt to do a read with full consistency, what does it mean if I get this error back?

zed relationship read someresource --consistency-full
Error: rpc error: code = OutOfRange desc = invalid zedtoken: revision has expired

More specifically, what is an expired fully consistent zedtoken? Should I be using a different consistency method if I don't have a zedtoken (and don't just want minimize latency)?