Race that excludes Dexterity from AC calculation

[CNYGamer]

Hi all.

I'm trying to set up the Tortle race and I'm having some difficulty with regards to AC calculation. A Tortle has a natural AC of 17, can't wear armor (but can use shields), and gains no AC bonus from Dexterity.

I found the following script in another race's natural armor:

if (hero.tagis[Hero.EquipArmor] = 0) then
     hero.child[ArmorClass].field[tACUnarDef].value = maximum(hero.child[ArmorClass].field[tACUnarDef].value,field[abValue].value)
endif

It doesn't explicitely prevent the character from equipping armor, but it does set base AC to whatever value is stored in abValue (in this case, 7).

Unfortunately, it also increases AC by the character's Dexterity modifier. So my two questions are:

1. Is there a way for me to exclude the Dexterity modifier from AC?

2. Is there a way to explicitely prevent the character from equipping armor?

Thanks much!