The defense factor is a number that, for the vast majority of equipment types, is scaled from 1-10 and represents a rough ability of that equipment to absorb firepower without being destroyed. Equipment is defined here, as items within the database, whether they are multi-man items like squads and teams, or singleton items like AFV's, and Guns, which also may be multi-man operated. Thus, you have guns which will be inoperable after a single direct hit having a DF of 1, unarmored vehicles with DF's of 1-2, untrained squads about 3-4, AFV's between 5-8, and trained infantry squads with DF's of 10.
Some airframes, most notably more modern pieces, and ships are the exception to this general rule, and scale higher.
It is important to understand the way that combat works in TOAW. In all fires, the number of shots fired at a force is determined by an attritional formula. Without revealing any exact formulae, it should suffice to visualize a number consisting of the sum of all firing equipment attack factors, divided by the sum of all defense factors as the basic attritional variable. This can then be modified further by deployment, terrain, special abilities, scales, attrition divider, target density, etc. These variations can be applied at the level of individual pieces, dependent on the conditions of the firing, and receiving units.
Now, this attritional value, call it A, then drives the calculations for how many shots are received by the opposing force. In AP combat, whether bombardment, or direct fire, all shots are considered lethal. This is true, as well, for the ten percent of AP fire strength that is applicable to armored targets, and bypasses the anti-armor calculations, and results in lethal hits. In anti-armor combat there are two additional calculations. The first is based on conditions in the receiving unit's hex, and is modified by the RCSB factor (a multiplier) which will determine if the shot "hits" the target. This is illustrated by the visibility/targetting matrix in the appendices. The second, is the chance to penetrate, which is also explained in the appendices. In TOAW III, the armor value also undergoes a weighted randomization to determine whether the hit was against frontal armor, or side armor, and at what angle of impact the hit took place. This modifies the chance to penetrate, as this changes the effective slope and thickness of the armor plate. Even after all of this, there are some chances for a hit piece to avoid destruction as it may "dodge" the hit (by virtue of its agile designation) or merely be damaged as opposed to being destroyed.
Anyhow, to reemphasize the third paragraph, when you see a terrain or deployment modifier working on the defense factor of equipment, this is changing the attritional value A applied against the unit. Multiplying the terms in the denominator by larger numbers, drives down A against the receiving unit. This makes the defender less likely to receive shots against its equipment. Modifiers to attack strengths of equipment are handled by multiplying the values in the numerator thereby increasing, or decreasing, A and the resultant number of shots against the receiving unit.
Hopefully, this helps explain what a DF is, and why changing numbers in the database without understanding the basic concept of TOAW's attritional model can lead to some pretty strange results if not done in a balanced, consistent, and well-tested fashion.
< Message edited by JAMiAM -- 10/31/2007 1:47:07 AM >