The main purpose of the cross-referencer, spxref, is to find
undefined predicates and unreachable code. To this end, it begins
by looking for initializations, hooks and public
directives to start tracing the reachable code from. If an entire
application is being checked, it also traces from
user:runtime_entry/1. If individual module-files are being
checked, it also traces from their export lists.
A second function of spxref is to aid in the formation of
module statements. spxref can list all of the required
module/2 and use_module/2 statements by file.