Definitions for "Reachable"
easily approached; "a site approachable from a branch of the Niger"
Keywords:  ref, latter, former, chain, tag
An object is reachable from a ref/ commit/ tree/ tag, if there is a chain leading from the latter to the former.
Keywords:  traversing, arrived, arcs, graph, nodes
The set of all nodes in a graph that can be arrived at by traversing arcs.
Being within reach.