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QUOTE (SR4A page 61 A NOTE ON MODIFIERS)
Shadowrun, Fourth Edition, uses four distinct types of modifiers: Attribute modifiers, Skill modifiers, threshold modifiers, and dice pool modifiers.
Attribute and Skill modifiers affect the character’s relevant stats directly, resulting in augmented Attribute Ratings and modified Skill Ratings respectively (see Attribute Ratings, p. 68, and Skill Ratings, p. 68). Threshold modifiers are situational modifiers that increase or decrease the thresholds of unopposed Success Tests and Extended Tests (see Thresholds, p. 63). Finally, dice pool modifiers are the most common type of modifiers; they represent dice pool increases and reductions from situational modifiers, the effects of augmentations, powers, spells, and from injuries, qualities, and various other sources (see Dice Pool Modifiers). These add and subtract from the dice pools but do not modify the basic Skills and Attributes in use.
The type of modifier in question is noted in the description of each modifier. Should there be any doubt, assume the modifier is a dice pool modifier.
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