  The set of distances of a monoid or of a domain is the set of all $d \in
\mathbb N$ with the following property: there are irreducible elements $u_1,
\ldots, u_k, v_1, \ldots, v_{k+d}$ such that $u_1 \cdot \ldots \cdot u_k = v_1
\cdot \ldots \cdot v_{k+d}$, but $u_1 \cdot \ldots \cdot u_k$ cannot be written
as a product of $l$ irreducible elements for any $l$ with $k < l < k+d$. We
show that the set of distances is an interval for certain seminormal weakly
Krull monoids which include seminormal orders in holomorphy rings of global
fields.
