  A large class of 5d superconformal field theories (SCFTs) can be constructed
by integrating out BPS particles from 6d SCFTs compactified on a circle. We
describe a general method for extracting the flavor symmetry of any 5d SCFT
lying in this class. For this purpose, we utilize the geometric engineering of
5d N=1 theories in M-theory, where the flavor symmetry is encoded in a
collection of non-compact surfaces.
