Modifier
base_modifier
no in-game name
The modifier base_modifier is a named modifier in Crusader Kings III; the game gives it no name. No add_…_modifier command in common/, events/ or history/ adds it. Patch 1.20.1.2, from game/common/modifiers/00_basic_modifiers.txt.
Effects
No modifier lines of its own. The script checks for it 0 times (has_…_modifier).
Where the game adds it
No add_…_modifier command in common/, events/ or history/ adds it.
Source: game/common/modifiers/00_basic_modifiers.txt (line 1), the English localisation (base_modifier, base_modifier_desc) and every add_…_modifier / remove_…_modifier in common/, events/ and history/, Crusader Kings III 1.20.1.2.