Hey all,
The behavior of those Relink filter operators is undefined because I didn't wish to lock their behavior down and have to remain backward compatible for them (for instance, I did make changes to their behavior between V1 and V2). They are highly specific toward Relink's internal needs, and if I could have prevented them from being publicly exposed, I probably would have.
However, I'm also finding out that a lot of people are starting to use those filters anyway, so it may be time for me to define them in the documentation and ensure ongoing support for them. There seems to be a demand for them.
-Flibbles