Hits below zero

If the H(B,E,I,F,C,En) of any body part drops below 0, the character is stunned and cannot react. If the current H(B,E,I,F,C, En) of a vital-area reaches original -B(B,E,I,F,C,En) the character must check if he stays alive . He must also roll if another hit is done. He must roll 50+ CON+cHt to stay alive. A vital-area is indicated by a in the damage table. To put it in a short explanation: Each time a combatan is hit and his cHt are or go -oHt, he must roll 50+CON-|n|, where n=(cHt) rounded down, and |n| is the absolute value of n. For all non-mathematics: 

$$\vert n\vert=\left\{ \begin{array}{ll} n & \textrm{if}\, n\geq 0\textrm{ }\\ -n & \textrm{if }n<0 \end{array}\right.$$

Keep in mind, that -4.5 is -4 not -5. Rounding negative real-numbers to integers is the same mechanism like rounding the positive numbers.

See also 14.1.4.

Example:

A character has 9 o/cHB at the head. He gets a damage of dHB 18 to the head, leaving him with -9 cHB at the head. He now must roll 50+CON-9 to stay alive. Another hit of dHB 5 reduces his cHB at the head to -14, again he must roll 50+CON-14. Another hit of dHB 6 reduces his cHB at the head to -20, so now he must roll 50+CON-20.