Considering a semicoherent system made up of n components having i.i.d. continuous lifetimes, Samaniego defined its structural signature as the n-tuple whose kth coordinate is the probability that the kth component failure causes the system to fail. This n-tuple, which depends only on the...

We introduce the concept of subsignature for semicoherent systems as a class of indexes that range from the system signature to the Barlow–Proschan importance index. Specifically, given a nonempty subset M of the set of components of a system, we define the M-signature of the system as the...

The subsignatures of a system with continuous and exchangeable component lifetimes form a class of indexes ranging from the Samaniego signature to the Barlow–Proschan importance index. These indexes can be computed through explicit linear expressions involving the values of the structure...