Standard functions are: sequential call, random call, repeat
call, recall, query number of waiting customers, change service group,
transfer customers to other types of services, enter number of transactions.
For standalone system, terminal can be used to program
system settings of ticket machine.
With PC based system, it supports user ID, log-on/log-off
to capture statistics of users and counters; no show, alert call, store,
view, and delete stored numbers, capture service groups.
