Basics
DV (Difficulty Value)
The number a check has to beat. 9 — simple, 13 — professional, 17 — hard, 21 and up — next to impossible.
For shooting, the DV comes from the range table: it depends on the weapon and the distance. Against knives and fists the DV is the target's Evasion roll, and only characters with REF 8+ can dodge bullets.