library(xref) of previous releases has been replaced by a much
more powerful tool, spxref, originally written by Tom Howland.
The main purpose of the cross-referencer is to find
unreachable code. To this end, it begins by looking for a definition
for user:runtime_entry/1 and also looks for initializations, hooks,
module export lists and
public directives to start tracing the reachable code from.
A second function is to aid in the formation of module statements. It
can list all of the required module/2 and use_module/2
statements by file.
See The Cross-Referencer.