 Here ordformula_141 denotes the order of formula_16 at formula_32.We have that ordformula_144 if formula_16 has a pole of order -ordformula_141 at formula_32, ordformula_148 if formula_16 is defined and non-zero at formula_32 and ordformula_151 if formula_16 has a zero of order ordformula_141 at formula_32.It can be shown that formula_16 has only a finite number of zeroes and poles, and thus only finitely many of the ordformula_141 are non-zero.