  If the vertices composing a network interact at distinct time points, the
temporal ordering of these interactions and the network's graph structure are
sufficient to convey the routes by which information can flow in the network.
Two networks with real-valued edge labels are temporally isomorphic if there
exists a graph isomorphism f:N->M that preserves temporal paths - paths in
which sequential edge labels are strictly increasing. An equivalence class of
temporally ismorphic networks is known as an isotemporal class. Methods to
determine the number of isotemporal classes of a particular graph structure
N(G) are non-obvious, and refractory to traditional techniques such as P\'olya
enumeration (P\'olya, 1937). Here, I present a simple formula for the number of
isotemporal classes of diasters, graphs composed of a vertex of degree a+1
connected to a vertex of degree b+1, with all other vertices of degree 1
(denoted D(a,b)). In particular, N(D(a,b)))=ab+a+b+1 if a is not equal to b,
and N(D(a,a)))=(1/2) (a^2+3a+2) otherwise. This formula is then extended to
five additional types of pseudograph by application of a theorem that states
N(G) is preserved between two graph types if edge adjacencies and automorphisms
are preserved, and provided that any two networks are members of the same
isotemporal class if and only if they are isomorphic by transpositions of
sequential edge labels on non-adjacent edges.
