In this paper we derive multivariable generalizations of Bailey's clas
sical terminating balanced very-well-poised 10 phi 9 transformation. W
e work in the setting of multiple basic hypergeometric series very-wel
l-poised on the root systems A(n), C-n, and D-n. Following the distill
ation of Bailey's ideas by Gasper and Rahman [11], we use a suitable i
nterchange of multisums. We obtain C-n, and D-n, 10 phi 9 transformati
ons combined with A(n), C-n, and D-n extensions of Jackson's 8 phi 7 s
ummation. Milne and Newcomb have previously obtained an analogous form
ula for A,, series. Special cases of our 10 phi 9 transformations incl
ude several new multivariable generalizations of Watson's transformati
on of an 8 phi 7 into a multiple of a 4 phi 3 series. We also deduce m
ultidimensional extensions of Sears' 4 phi 3 transformation formula, t
he second iterate of Heine's transformation, the q-Gauss summation the
orem, and of the q-binomial theorem.