diff --git a/systems.tex b/systems.tex
index a5561646fc759765f60d5a5661677c47823db4ff..6a2d0c5dd8f44f98b2fe92b67cf7e9b82ccf87f0 100644
--- a/systems.tex
+++ b/systems.tex
@@ -246,6 +246,9 @@ They may divide these \glspl{fatigue} in any way, so one person could keep watch
 
 \makeRule{climbing}{Climbing}{Speed}{Athletics}{varies greatly}
 
+Rolling a tie indicates that the climber knows they cannot make the climb, or at least fails on the first few holds.
+Failure with a Margin of 1 gives the worst possible result -- the climber fails while near the top, while a larger failure Margin means they travelled less far before falling.
+
 \makeRule{detect_sloping}{Detect sloping passages}{Wits}{Caving}{10}
 Understanding what altitude one has reached immediately indicates whether there might be running water, what type of rocks and minerals compose the surroundings (and therefore the chance of a cave-in), and how far one has to go to the surface.