Diplomatic Veterancy comparison chart

== Comparison of Veteran effectiveness: Diplomat vs Military combat ==
Comments in Freeciv code lead us to believe that veteran levels for diplomats should be much lower than their equivalents for military units, due to how they are used in various formulas. The formulas affected by the veteran level of a diplomat are:
* Diplomatic combat
* Chance of escape { (game.server.diplchance + (power_fact-100) } %
Odds of operation success are unaffected by veteran level!
Consequently, if a game has a high diplchance like 80%, any veteran power_fact over 120 would always escape successfully after a successful mission. (But not necessarily succeed in the mission, where veteran level counts for nothing!)
If keeping escape chance at "nearly always" but never allowing it to sometimes be "always" is the most important priority, then this "unwritten rule" of not going over power_fact 120 is important.
But let's view the consequences of keeping diplomatic power_fact very low, on other game mechanics. The other formula that is influenced by power_fact is diplomatic combat itself. The tables below compare how power_fact formulas for diplomatic combat compare with power_fact formulas for military combat, vis-à-vis odds of success:
=== Military veteran levels vs diplomatic veteran levels and odds of success ===
*Odds of success vs. v0 "green unit". 10hp attacker vs 10hp defender is assumed 
 	Military power_fact	odds	Diplomatic power_fact	
v0	100 	50% 	100 	v0
v1	150 	81% 	131 	>v3
v2	175 	89% 	139 	>v3
v3	200 	94% 	144 	>v3
Conclusion: a v1 vet military unit has higher odds of success than the highest elite vet level for a diplomat.
 	Diplomatic power_fact	odds	Military power_fact	
v0 	100 	50% 	100 	v0
v1 	105 	55% 	106 	<v1
v2 	110 	60% 	112 	<v1
v3 	115 	65% 	119 	<v1
"4"	120 	70% 	127 	<v1
"5"	125 	75% 	136 	<v1
"6"	130 	80% 	147 	~v1
"7"	135 	85% 	160 	<v2
Conclusion: A hypothetical "v6" diplomat with power_fact 130 is required in order to get the same odds as a v1 military unit.
Final conclusions:
* If one wants there to always be a SMALL chance of getting caught, the price one pays is that diplomatic veteran levels mean almost nothing, unless diplchance is lowered. If diplchance were lowered, then power_fact could be much higher, but veterancy would be much harder to achieve since successful missions would be much less likely.
* If one doesn't care that high veteran diplomats always escape from a successful mission, and suffer the greatest chance of dying from the mission itself (where veteran level has no influence on odds of success), then the preferred path is to amplify the power_fact for diplomatic veteran levels. Specifically, the typical military vet levels of 100,150,175,200, would have the approximate equivalent diplomatic levels of 100, 130, 140, 145. A very low chance of getting caught after a successful mission would be lost. But for vets, the chance of capture was always greater from the mission being unsuccessful anyway.
Possibilities for future refinement:
This line of code in diplomats.c::diplomatic_escape_full(), would have to change:
 escapechance = game.server.diplchance + (vunit->power_fact - vbase->power_fact);
By making the power_fact proportionally span the distance between diplchance and 100, the ability for spies to be caught after successful missions would be preserved WHILE allowing diplomatic veteran levels in diplomatic combat to normalize to the standards to which we are accustomed in normal military combat.