This also applies to cable, chain, and webbing.
Gear that is anchored includes anchors, rocks, trees, tripods, trucks, etc.
A "bight" is a simple loop in a rope that does not cross itself.
A "bend" is a knot that joins two ropes together. Bends can only be attached to the end of a rope.
A "hitch" is a type of knot that must be tied around another object.
"Descending devices" (e.g., ATCs, Brake Bar Racks, Figure 8s, Rescue 8s, etc) create friction as their primary purpose. The friction in descending devices is always considered when calculating forces.
The "Safety Factor" is the ratio between the gear's breaking strength and the maximum load applied to the gear (e.g., 5:1).
vRigger can display "overload symbols" to warn you of a potentially overloaded system.
Forces are within limits.
Forces exceed your safety factor.
Forces exceed the gear's strength.
Overload symbols are enabled/disabled in the Safety Factors group on the Forces toolbar.
As with force labels, overload symbols can only be displayed after the forces have been calculated. If anything changes in the system, the overload symbols will be removed.
You can set the gear's breaking strength in the Forces section of the properties pane. The breaking strength can be entered in kilograms (Kg), kilonewtons (kN), or pounds (Lb).
If the force on gear exceeds the gear's strength (as defined in the properties pane), the 
symbol is displayed on the gear to warn you that it will fail. If the force on the gear multiplied by the safety factor (as defined in the Safety Factors group on the Forces toolbar) exceeds the gear's strength, the 
symbol is displayed to warn you that the safety factor has been exceeded.
Remember, overload symbols are only displayed if the Overload Symbols checkbox is selected in the Safety Factors group on the Forces toolbar and if the forces have been calculated.
REMINDER: The force calculations in vRigger are calculated based on a static, two-dimensional computer screen—the values can vary in the "real world." It is your responsibility to understand the strength of your rigging systems.