Straight out of Runner's Companion:
"Shapeshifters look mostly human—normally. Through some quirk of magic or paragenetics, some shapeshifters can transform into a form that more closely resembles another metatype, or even metavariants. This is represented by changing their Shift (Human) power to another, as appropriate—Shift (Elf), Shift(Oni), etc.—and spending an additional number of BP equal to the typical cost for that race –10 BP. A shapeshifter with a different metatype GAINS* their standard metatype abilities (see Metatype Attribute Table, p. 72, SR4) when in that form."
*Emphasis added.
Correct me if i'm wrong but the way i am reading this is that if you decide to create a character that is a shapeshifting Eagle who startts with Attributes at:
Body 1/6(9)
Agility 1/6(9)
Reaction 1/6(9)
Strength1/6(9)
Charisma 2/7(10)
Intuition 1/6(9)
Logic 1/6(9)
Willpower 3/9(13)
Then I spend the extra BP to give the character the Shift(Elf) power the base attributes in metahuman form will end up as:
Body 2/7(10)
Agility 3/8(11)
Reaction 2/7(10)
Strength 2/7(10)
Charisma 5/10(13)
Intuition 2/7(10)
Logic 2/7(10)
Willpower 2/7(10)
Am I right or am i just confused?