In Smac a fourth element was introduced, namely strength.

Now I can already see something common with Advanced Dungenos and Drugons (ADD) that I played in my youth.
In ADD a character was described in battle by:
- hitpoints (HP)
- Armor (A)
- Speed (S)
- Wepon attack (WA)
- Wepon damage (WD)

HP: How many hits yoiu could take. (=health)
A: How well you had protected yourself
S: How often you could use your wepons (A combination of wepon and your character)
WA: What is the possibilty of successfull attack
WD: In case of succesfull attack, how much damage will the wepon couse

Think about it...
You could have a rifelmen very good in S and WA, but lousy in WD and a tank with poor S and WA, but great in WD.
This could lead to you getting a different types of units at different time of play.

Example panzer.
In the beginning (WWI) they were armored wagons with machine guns, so:
- HP: Poor/Medium (Easily destoyed)
- A: Poor (Very light armor)
- S: Medium (Well back then...)
- WA: Medium/Good (Machine guns are quite easy to target with in close combat)
- WD: Poor (Bullets do little damage. Max 1 dead/bullet even less)

Then they became slowly better with cannontowers etc. The development wasn't as fast on all fronts though.
In WWII tanks became heavier and heavier so WD could increase. (See Yog-Sothoth post)

After WWII came faster units S with same WD and with computers theire WA increased.