decision (Z.100)

Concrete graphical grammar

<decision area> ::=
<decision symbol> contains <question>
is followed by
{ {<graphical answer part> <graphical else part>} set
| {<graphical answer part> {<graphical answer part>}+
[<graphical else part>] } set }

<decision symbol> ::=

<graphical answer> ::=
[<answer>] | ([<answer>])

<graphical answer part> ::=
<flow line symbol> is associated with <graphical answer>
is followed by <transition area>

<graphical else part> ::=
<flow line symbol> is associated with else
is followed by <transition area>

<question> ::=
<question expression> | <informal text> | any;

The <graphical answer> and else may be placed along the associated <flow line symbol>, or in the broken <flow line symbol>.

The <flow line symbol>s originating from a <decision symbol> may have a common originating path.

The <answer> of <graphical answer> must be omitted if and only if the <question> consists of the keyword any;. In this case, no <graphical else part> may be present.


A decision transfers the interpretation to the outgoing path whose range condition contains the value given by the interpretation of the question. A set of possible answers to the question is defined, each of them specifying the set of actions to be interpreted for that path choice.

One of the answers may be the complement of the others. This is achieved by specifying the else answer, which indicates the set of activities to be performed when the value of the expression on which the question is posed, is not covered by the values or set of values specified in the other answers.

Whenever the else answer is not specified, the value resulting from the evaluation of the question expression must match one of the answers.