We study the commutative algebras ZJK appearing in Brown and Goodearl's extension of the H-stratification framework, and show that if A is the single parameter quantized coordinate ring of Mm,n, GLn or SLn, then the algebras ZJK can always be constructed in terms of centres of localizations. The main purpose of the ZJK is to study the structure of the topological space spec(A), which remains unknown for all but a few low-dimensional examples. We explicitly construct the required denominator sets using two different techniques (restricted permutations and Grassmann necklaces) and show that we obtain the same sets in both cases. As a corollary, we obtain a simple formula for the Grassmann necklace associated to a cell of totally nonnegative real m × n matrices in terms of its restricted permutation.The key technique in the study of spec(A) is that of H-stratification, where H is a torus acting rationally on A. Write H-spec(A) for the set of H-primes: the prime ideals of A which are also invariant under the action of H. The H-primes induce a stratification of spec(A), where for each J ∈ H-spec(A) the associated stratum isThis stratification has many nice properties. In particular, each spec J (A) is homeomorphic to the prime spectrum of a commutative Laurent polynomial ring Z(A J ), which can be constructed explicitly as the centre of a localization of A/J [3, Theorem II.2.13]. These algebras Z(A J ) are now reasonably well understood, e.g. [1,25].This approach gives us an excellent picture of the individual strata, but it comes at the cost of losing information about the interactions between primes from different strata. Being able to identify inclusions of prime ideals from different strata is crucial for constructing a complete picture of the topological structure of spec(A), but this information is often surprisingly difficult to obtain: for example, in the setting of quantum matrices only the prime spectra of O q (SL 2 ), O q (GL 2 ), and O q (SL 3 ) ([15], [2], [7] respectively) have been fully described.