mcxsubs(1) on Linux
The text 2f74303baec2, as Debian 3.0 (Woody) shipped it.
extract submatrices (subgraphs) of a matrix (graph) corresponding with index sets and sets of clusters. This can be used to inspect local cluster structure in a graph, for example by looking at the subgraph induced by a single cluster or a couple of clusterings, or the edge set where all tail nodes are from a set of clusters and all head nodes are from the complement of this set, and many other variants and refinements.