Page 122 - Intelligent Communication Systems

CHAPTER 9 / DESIGN METHODOLOGY FOR TELECOMMUNICATION SERVICES I 01
(4) Action is defined as follows.
Input of service information: input of user number, input of
authentication
Change of service state: activation or deactivation of service
subscription or nonsubscription of service
Change of terminal state: universal personal telephone (UPT), local
terminal, and home terminal
• Call forwarding variable: forwarding terminal and forwarded
terminal
• Person-to-person call: caller terminal and called terminal
• Change of terminal: terminal activation or deactivation
• Change of line state: converse, disconnect, or hold
All of these terminal states are listed and stored as an ontology of terminal states.

9.8 REQUIREMENT SPECIFICATION

(1) The requirement specification is described in natural language as follows.
When the initial states are Si{, Si} and an action a is taken, the states are moved
to So{, So}, where Si and So are states, a is an action, and {S} shows iteration.
(2) The requirement specification form is interpreted as in the following
example: When onhook(A) is performed at the terminal state path(A, B), then the
terminal state is moved to idle(A). The validity of Si and So is checked by using
the ontology of the terminal states shown in Figure 9.18. The validity of a is
checked by using the ontology of the terminal actions shown in Figure 9.19. If Si,
So, and a are valid, then the form is translated to an STR form.