[fennecfoxen]

To generalize, "possible match detected" for anything: you have a big, fat database about a bigger, fatter universe of identifiers, and a less-capable set of clients over a less-capable network link. They want a fast way of determining whether or not a particular identifier is worth querying the database for, and the false positives do not have a very high cost.

The conditions are relevant for some cloud-managed appliances, mobile-phone applications, and sometimes caching techniques in your own distributed applications.