The service mapping module stores {TAIL ~ a table} that maps {HEAD ~ services} to access point names 
The service mapping module stores { TAIL ~ a table } that maps { HEAD ~ services } to access point names
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH