Data Definition Of Data Flow Diagram Operators
Composite data items can be defined in terms of primitive data items using the following data definition operators.
+: (plus sign) denotes composition of two data items, e.g. a+b represents data a and b.
[,,]: (square bracket with comma inside) represents selection, i.e. any one of the data items listed inside the square bracket can occur For example, [a,b] represents either a occurs or b occurs.
(): (parentheses or circle bracket) the contents inside the bracket represent optional data which may or may not appear.
a+(b) represents either a or a+b occurs.
{}: (curly bracket) represents iterative data definition, e.g. {name}5 represents five name data.
{name}* represents zero or more instances of name data.
=: represents equivalence, e.g. a=b+c means that a is a composite data item comprising of both b and c.
/* */: Anything appearing within /* and */ is considered as comment.
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