Here is a list of all files with brief descriptions:

asctime.c
date.c
difftime.c
ialloc.c
localtime.c
private.h
pscan.cpp
scheck.c
strftime.c
tzdata.cpp
tzdata.h
tzfile.cpp
db/tzfile.h
include/tzfile.h
tzhelp.h
tzreg.h
tzsys.h
tzsys_unix.cpp
tzsys_win.cpp
version.h
zdump.c
zic.c
zonefiles.cpp