The nodes (Except those of C or D type) can have a subscript or index that can take values 1, 2, ..., until a maximum value that must be declared by the user in the node heading. Indexed nodes are equivalent to a set of nodes of the same type equal to the declared maximum. These nodes share a common code. They are used to represent sets of similar subsystems.
When activated during the scan of the network, they are activated sequentially. When activated by an event that refers to I and A type nodes, only the node with the index of the event is activated. An index variable INO takes the value of the index of the currently executed node. The user has access to that index in order to be able to control differences when processing the common code. The multiplicity or dimension of the node is declared as arrays in PASCAL, i.e., in the form [1..N].
Example:
Window (R) [1..5] Exit1, Exit2 :: <code>This line declares that the node named Window is of R type, its successor nodes are Exit1 and Exit2. It consists in 5 nodes that share the
<code>. The nodes without index are called simple, those with index are called multiple nodes. The number of nodes of a multiple node is called its dimension or multiplicity.
The nodes of a multiple R type node can be of different capacity.