We construct subgroups of the
Brauer group of an algebraic number field whose member classes have Hasse
invariants satisfying a rigid arithmetic structure — that of (relative) uniform
distribution. After obtaining existence and structure theorems for these subgroups,
we focus on the problem of describing algebraic properties satisfied by the central
simple algebras in these subgroups. Key results are that splitting fields are
determined up to isomorphism, and there exists a distinguished subgroup of central
automorphisms which can be extended.