Skills, Checks, and Modifiers
The System supports Palladium-style percentile skills as structured Skill records. A Skill can carry a base proficiency, an improvement rate, one or more categories, prerequisites, restrictions, special notes, and other data supplied by the World. The Character stores which skills that individual has and can preserve the level or point in the career at which the skill was acquired.
When to roll
Use a skill check when the active World calls for one and the outcome is meaningfully uncertain. Routine actions that the rules or fiction make automatic do not need a roll simply because a percentage is visible on the sheet. When a roll is required, use the proficiency and modifier procedure defined by the World.
Many Palladium games use percentile resolution for skills, but the System does not hard-code one universal maximum percentage, one universal critical-failure range, or one universal I.Q. bonus table. Those details are configuration. If a World says a particular skill has a special roll, a cap, a prerequisite interaction, or a different advancement rule, use the specific rule.
Current proficiency
A character's current skill value can depend on several sources: the Skill definition, O.C.C./R.C.C. training, an attribute rule, a learned-at-level offset, physical or educational bonuses, equipment, temporary effects, or World-specific modifiers. The Character's computed fields should do the arithmetic when the data is available. Do not recalculate the same number from memory if Craft already exposes the derived value.
Permanent training and temporary situational modifiers should remain distinguishable. A bonus earned through class progression belongs in persistent character data or the referenced definition. A penalty from darkness, injury, stress, poor tools, or another temporary situation should not permanently rewrite the base Skill.
Learned later
The Character can record when a skill was learned. This lets a World support rules in which a newly acquired skill begins at its own first level of proficiency even when the character is already more experienced overall. The exact advancement formula is still World-defined, but the state required to implement it is present.
Categories and eligibility
Skill Categories are organizational definitions, not a shortcut for permission. A skill can belong to more than one category, and a class can restrict or grant particular skills independently of category. When the source game says the exact skill controls eligibility, follow the exact skill. When a class grants a prerequisite automatically, encode that rule in the World instead of forcing the player to reverse-engineer it from category names.
Modifiers are typed
Not every modifier is a flat number. A World may use percentages, dice, thresholds, textual exceptions, or conditional bonuses. The engine should apply only modifiers whose target, unit, source, and condition make sense for the current check. Do not add a dice expression or a text note as though it were a numeric bonus.
The guiding principle is simple: the System provides the place to store and calculate skill mechanics; the World defines the actual numbers and exceptions.