A unit gets his built-in traits from these tags in XML (CoreUnits.xml and CoreMonsterTypes.xml):

        <SelectedAbilityBonusOption>Blood_Amarian</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>Guardian1</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>Air1</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>Air2</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>Air3</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>PathOfTheDefender</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>PathOfTheWarrior</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>Spell_ChainLightning</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>Strength_Level</SelectedAbilityBonusOption>

the abilities are in CoreAbilities.xml

    <AbilityBonus InternalName="Guardian1Ability">
        <AbilityBonusType>Unit_Level</AbilityBonusType>
        <AbilityBonusOption InternalName="Guardian1">
            <DisplayName>Guardian I</DisplayName>
            <Description>+2 to the Army's Dodge</Description>
            <Icon>Ability_GuardianI_Icon.png</Icon>
            <GameModifier>
                <ModType>Unit</ModType>
                <Attribute>AdjustArmyStat</Attribute>
                <StrVal>UnitStat_Dodge</StrVal>
                <Value>2</Value>
                <Provides>+2 to the Army's Dodge</Provides>
            </GameModifier>
            <Likelihood>200</Likelihood>
            <RarityDisplay>Uncommon</RarityDisplay>
            <Type>Army</Type>
            <Prereq>
                <Type>AbilityBonusOption</Type>
                <Target>Unit</Target>
                <Attribute>PathOfTheDefender</Attribute>
            </Prereq>
            <AIData AIPersonality="AI_General">
                <AIPriority>5</AIPriority>
            </AIData>
        </AbilityBonusOption>
    </AbilityBonus>

also Likelihood determines chance that it appears on level-up. Prereq and other tags may limit according to level.

If you look at PathOfTheWarrior (in coreabilities.xml)  you'll see at the end of it that

That likelihood being 1 means it always appears?  Also using the tags Minimum Level  and Required Level I was able to give my new paths ability to be chosen at level 8. The way I am doing it is I have made a abilities.xml file in its own folder for that mod in my mods folder.  Since I am merely adding content, I am leaving the core files alone. 

This is an example of one of the paths that come at level 8 if you had picked Path of the Assassin earlier. 

This is an example of a Path I made that shows up at level 4 along with the others.  It's called Archer.

 You can then use those internal names as pre-reqs for new abilities you make and/or spells.  I could easily make a spell require say "PathOfTheRedMage" in addition to "Water2" by just adding in more prereqs tags.. 

sorry for the wall of text.  Wish I could show/hide it.  Well that's how I've done it so far. 

Thank you. More details Please. which of these lines affect the game:

1.                 <Value>3</Value>
2.                 <Provides>+3 Attack</Provides>

is there a limit to the number here is just such lines (the number of such operations in general. and the number of filled in) :

1.             <GameModifier>
   ...
   
2.             </GameModifier>

For example Altar faction (CoreRaceConfigs.xml = KingdomOfAltar)  is made up of race Altarians (<RaceInternalName>Race_Type_Altarians</RaceInternalName>).

In CoreRaceTypes.xml you see "Race_Type_Altarians" with links to many unittypes, example: <StartingUnitType>Unit_Archer_Altarian</StartingUnitType>

If you then go to CoreUnits.xml you see "Unit_Archer_Altarian" which has the trait: <SelectedAbilityBonusOption>Blood_Altarian</SelectedAbilityBonusOption>

That is how you add traits to a full race.

Yes.

CoreRaceTypes.xml

        <MaleUnitType>Generic_Sovereign_Altarian_Male</MaleUnitType>
        <FemaleUnitType>Generic_Sovereign_Altarian_Female</FemaleUnitType>

you see same name in CoreUnits.xml

<UnitType InternalName="Sovereign_Relias">
        <DisplayName>Lord Relias</DisplayName>
        <UnitDisplayName>Lord Relias</UnitDisplayName>
        <Class>Sovereign</Class>
        <Allegiance>Kingdom</Allegiance>
        <CreatureType>Champion</CreatureType>
        <RaceType>Race_Type_Altarians</RaceType>
        <Unique>1</Unique>
        <CanBeDesigned>0</CanBeDesigned>
        <FactionToLead>KingdomOfAltar</FactionToLead>
        <Gender>Male</Gender>
        <HasWages>0</HasWages>
        <IsSovereign>1</IsSovereign>
        <HasEssence>1</HasEssence>
        <SelectedAbilityBonusOption>PathOfTheDefender</SelectedAbilityBonusOption>
        <SelectedAbilityBonusOption>PathOfTheWarrior</SelectedAbilityBonusOption>
        <GameModifier>
            <ModType>Resource</ModType>
            <Attribute>Unrest</Attribute>
            <Value>-10</Value>
            <Provides>-10% Unrest in the city this unit is in</Provides>
        </GameModifier>
        <GameModifier>
            <ModType>Player</ModType>
            <Attribute>AbilityBonus</Attribute>
            <StrVal>A_FactionPrestige</StrVal>
            <Value>0.5</Value>
            <PerLevel>1</PerLevel>
            <Provides>+0.5 Faction Prestige per Level</Provides>
        </GameModifier>
        <LevelMilestone InternalName="L1">

this will work? or how to write?

strange. checked. no sovereign in these ways. I do not quite understand sinteksis. but copy what I wrote above.
coreunits like just one.

I just started playing through Steam. from the fact that the forum name changed (when loading the game to give an error showing how to register the incentive start). had the incentive to register a login and password. so do not get tested.

Yes, I too do not understand. may name a different way had to write? It has two names (in another "abilites" at the end sort of)

1. I have problems with running the game. I can not run it from the Administrator mode. I can just run it through Steam.
2. A mistake in writing? Append had only CoreUnits.xml? If so, you can throw a working version? Or had to go somewhere else to add? For example here "CoreRaceTypes.xml"

http://i081.radikal.ru/1209/c0/b117197f142b.png

it is long overdue. now I do not run a game in exe. now only steam

tried. did not help. will update the game to 0.99
Experiment in the future even

In order for it to work with core units you might have to run the game in admin mode. This was an issue for me as well.