In this act, unless the context otherwise indicates,
(a) "Tax advantage" refers to income or wage taxes, and means (1) a less inclusive definition of taxable income or wages, (2) a lower rate of tax, (3) a greater number of or amount of available exemptions, or (4) a greater number or amount of available deductions, or any of the foregoing, and
(b) "Foreign taxing jurisdiction" or "jurisdiction" means a sister State or any municipality or other subdivision of a sister State which imposes a tax on the income or wages of residents of this State from sources within such jurisdiction.