Sappers

In reconquest phase 2, on the resistance sappers stat line under special there is the ability infiltrate-18. I've looked in all 3 books and can't find anything on what that means, even the rules update doesn't say anything about it. Is it an obsolete experimental rule left in by mistake? If it is supposed to be there what does it mean?

It is supposed to be in the errata as it was added to Req 1, though apparently it got lost in transition. I hope Liam can help on the matter.

IIRC, it means that so long as they don't take a transport they can always direct deploy X" (in this case 18") from your table edge.
Generally in a building that you feel will matter.